Reasoning for this request is a bit complex. Therefore, first explained by another game, Civilization.
What is to some extent a relevant part of the various Civ games?
Building wonders.
But only the first to build gets the wonder.
On low difficulties, it is possible to build nearly all or all wonders.
What happens with increasing difficulty, or in other words increasing starting bonuses and increasing constant percentage bonus (to production, research, gold, etc.)?
It is more and more difficult to build wonders, because the AI bonuses are more and more likely to ensure, that one cannot finish ANY wonder first, neither the early (cause the AI has simply enough cities for building wonders, and you need 1 per wonder) nor the late (cause AI has a constant tech lead and therefore a head start on any one)
That does mean that with certain starting/percentage bonuses it is not only less likely to succeed in building wonders, but actually trying to build them turns more and more into a WRONG decision.
Hence, with increasing constant and especially starting bonuses, the game play element "building wonders" fades out into irrelevance (at maximum difficulty, you conquer them, if you want them).
On the other hand, the build options "settlers" and "military units" do not fade out. While on low difficulty on a continent with 1 AI, one might end up getting 2/3 of the good spots, and then face the AI with a 1,5 to 1 military advantage, and on high difficulty same map one might end up with just 1/3 of the good spots and face AI outnumbered 1 to 3, you still have to build "settlers" und "military units" and put them to use - it just got more difficult.
So with some game mechanics, both constant and especially starting bonuses can fade out some game play elements. Namely, the ones with "winner takes it all".
On the other hand, if instead of fewer starting and constant bonuses, the Civ AI had an increasing bonus (e.g. (formula[number of turns])% to production, research, etc.) at least in the early game "building wonders" would still be an option, and maybe even in the later game, if you managed to keep up with the improving AI advantage.
So a bonus scaling with turns has a different effect on "winner takes it all" elements.
In CoM the treasure from lairs, towers, nodes is "winner takes it all".
Hence, there is also in CoM an effect that constant AI bonuses (are there any starting ones?) on higher difficulties at least reduce the relevance of the game play element treasure hunting - cause while one can still use units and settlement decisions to compete with the AI, if AI is nearly guaranteed to have the units necessary to knock out powerful lairs, nodes, towers, one can do not that much (but certainly the issue is far less as in Civ wonder building, as even on highest difficulty you can do some treasure hunting).
And this is not meant as an instead, but alternatively/additionally.
It could be rather easy to implement, e.g. an option to select a starting difficulty, a maximum difficulty, and an interval after which difficulty goes one up (I think Civ4 mod fall from heaven had that option). Of course, there might also be other options (for new MoM i am currently trying out how AI fares with 2*turn food and 1*turn power bonus from fortress, cause new MoM AI is horrible at defending his settlements).
Also, it could give an alternative game experience with an easy start, which has to be put into good use for the dire end.
(and if you know civ iterations, which on highest difficulty still have wonder building - that is because the AI is designed not to use his advantage to grab all wonders; but making AI not make optimal use of his resources is not CoM design)
What is to some extent a relevant part of the various Civ games?
Building wonders.
But only the first to build gets the wonder.
On low difficulties, it is possible to build nearly all or all wonders.
What happens with increasing difficulty, or in other words increasing starting bonuses and increasing constant percentage bonus (to production, research, gold, etc.)?
It is more and more difficult to build wonders, because the AI bonuses are more and more likely to ensure, that one cannot finish ANY wonder first, neither the early (cause the AI has simply enough cities for building wonders, and you need 1 per wonder) nor the late (cause AI has a constant tech lead and therefore a head start on any one)
That does mean that with certain starting/percentage bonuses it is not only less likely to succeed in building wonders, but actually trying to build them turns more and more into a WRONG decision.
Hence, with increasing constant and especially starting bonuses, the game play element "building wonders" fades out into irrelevance (at maximum difficulty, you conquer them, if you want them).
On the other hand, the build options "settlers" and "military units" do not fade out. While on low difficulty on a continent with 1 AI, one might end up getting 2/3 of the good spots, and then face the AI with a 1,5 to 1 military advantage, and on high difficulty same map one might end up with just 1/3 of the good spots and face AI outnumbered 1 to 3, you still have to build "settlers" und "military units" and put them to use - it just got more difficult.
So with some game mechanics, both constant and especially starting bonuses can fade out some game play elements. Namely, the ones with "winner takes it all".
On the other hand, if instead of fewer starting and constant bonuses, the Civ AI had an increasing bonus (e.g. (formula[number of turns])% to production, research, etc.) at least in the early game "building wonders" would still be an option, and maybe even in the later game, if you managed to keep up with the improving AI advantage.
So a bonus scaling with turns has a different effect on "winner takes it all" elements.
In CoM the treasure from lairs, towers, nodes is "winner takes it all".
Hence, there is also in CoM an effect that constant AI bonuses (are there any starting ones?) on higher difficulties at least reduce the relevance of the game play element treasure hunting - cause while one can still use units and settlement decisions to compete with the AI, if AI is nearly guaranteed to have the units necessary to knock out powerful lairs, nodes, towers, one can do not that much (but certainly the issue is far less as in Civ wonder building, as even on highest difficulty you can do some treasure hunting).
And this is not meant as an instead, but alternatively/additionally.
It could be rather easy to implement, e.g. an option to select a starting difficulty, a maximum difficulty, and an interval after which difficulty goes one up (I think Civ4 mod fall from heaven had that option). Of course, there might also be other options (for new MoM i am currently trying out how AI fares with 2*turn food and 1*turn power bonus from fortress, cause new MoM AI is horrible at defending his settlements).
Also, it could give an alternative game experience with an easy start, which has to be put into good use for the dire end.
(and if you know civ iterations, which on highest difficulty still have wonder building - that is because the AI is designed not to use his advantage to grab all wonders; but making AI not make optimal use of his resources is not CoM design)