I'll address different points separately.
I think you are confused with time frame and remember everything in tainted rose glasses. Lethality was higher back then (double weapons, 1919s, Obers, mortars, artillery, etc.)
There were 2 time frames on which small arm fire lethality was low. 2013 game release on which units takes eons to die and maxim/MG42 was a thing (which led to small arm fire rework and 1.25 RA weapon crews) and beginning of 2016 when ALL OFFENSIVE VETERANCY ON INFANTRY didn't work at all.
https://www.coh2.org/topic/49473/gamebreaking-veterancy-bug
Plenty of yellow cover giving 0.50 RA + natural RA gained through vet offsets any of the weapon upgrades on units, which is the reason it was not discovered faster. Once you fixed that shit, suddenly ALL infantry units gain access to around +40% improvement on the offensive department.
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Micro/APM. I don't think that the game has gone up in any case and it's not even close to ALL other RTS out there.
What is has change is that BLOBBING and relying on FOTM META OP units is slightly harder. There's nothing wrong with blobbing or playing meta, it's the dunning Krugger effect that it's an issue.
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People taking breaks and expectations.
If you were to not do exercise for 2 years and then decided to run a short marathon in a glimpse without preparation at all, i will feel sorry for your lungs and heart.
Just because you were USED to do something in the past, doesn't mean it will hold it's ground in the present. If you keep getting old and launch the game when you are already stressed out from work having your brain operating at 50%, don't blame the game. You are just on the other side of the coin when back then you were defeating this kind of people as well.
All if not most PvP games evolve and change with time. If you are not aware of the meta/change you will struggle.
If your fun comes ONLY from seeing the victory screen, then i feel sorry for you. I think the game does a very bad job with ELO/MMR decay so it will take some time before those numbers goes down till you face people at a similar skill bracket.