A lot of people seem to misread OP and diverge the topic into once again another complaint of “no longer simple/pure/chess or whatever” then “don’t introduce new features”.
I think OP is suggesting the opposite: if you want to introduce a new mechanics, give it to everyone. Not to the new civ exclusively.
That’s exactly what I suggested with AOE3DE DLC civs: they once introduced the one and only civ that has better mercenaries, while the rest still cannot utilize this feature well. Same goes for natives, livestock, revolution, etc. They even introduced new European natives exclusively accessible to new European civs not the old ones (some of which are far more relevant).
However thankfully through constant updates most civs are enriched to a similar level of mechanics/contents. That’s what I think OP would like to see regarding new mechanisms.
Well unexpectedly people began another round of “no longer simple/pure/chess“ but that’s a totally different topic.
I even used the exact same wording XD
It’s not necessarily power creep or p2w. It’s not always going to break balance. It just causes inconsistencies in the interesting-ness of civs.