I doubt that's the casePlayers are turned off by many other things, and you can probably sum up most negative reviews with the same 5 bullet points. Relic didn't do much to address those since launch, and won't in the near future either.
But even if we assume that players were just "too dumb" to play the game: That's actually Relic's fault. Relic apparently didn't manage to design the game for their target audience. The system seems to be too dubious and not intuitive, maybe too complicated to learn. If they aimed for a dedicated niche audience that's willing to invest that time and learn it, it would be fine. They didn't. They aimed for and marketed to casual gamers. Those don't want to spend as much time as they'd need to learn 1v1 play style. Relic missed their target audience and programmed the wrong game for them. That's a bad decision from Relic, at least from a business perspective, even if the game under these aspects is good.
But this also raises the next issue: They designed their game for 1v1, but most players and most offered game modes are team games. Which also means they missed their own aims for game design.
I believe you when you say that CoH3 is solid in some aspects and for a specific player base, but it is far from what Relic expected and needed to keep the game healthy.
Players are not too dumb to play the game but they are definitively to believe they know the game because they have xK hours on Coh1/Coh2 Franchise and post clueless negative review of it. I read many on Reddit and they're just 2/3 empty of arguments.
Only points I fully agree against Coh3 atm.
1- lack of maps.
2- Lack of multiplayer ranking assets.
The rest of it are just people surfing the negative hype to avoid saying they just suck at it. There is the usual unbalance random teamgame provides, that was in Coh1 and in Coh2 until the game got rebalanced to the point 1vs1 become boring, just to satisfy people that don't want to make a friend list to play teamgame and cry because one side get it more easily on random.
2/3 of teamgame players trashing coh3 don't have a clue on how to play the game, they say it themselve all the time, they scared to play 1vs1 to get their bump bump smashed, why? Because they don't know to play the game, they don't know 1/3 of game mechanisms and go on teamgame with the hope the people they're going to be match with will carry them enough to win. And guess what, that doesn't happen because those players represent too big portion of the player base on team game, they are match together and get smash together.
And then, they switch side, and guess what again, they only do the same shit, they spam team weapon and arty and ooooh they win, but did they learn something? no, nothing. And then they come to Reddit and say how the game is poorly design and has a poor gameplay blablabla...
Coh3 is more elitist than coh2, they are more mechanism, more abilities than in coh2 to be learnt and understood and truly the average Joe that just want to do a game after work is going to suffer a lot just to grasp enough knowledge to play the game at a correct level.