Why are you trying to gatekeep ?
You do realize that your first point requires more players to play the game, but your remaining points are gatekeeping these players from joining and playing the game ?
If random Bob sees cool intro cinematic from original AoM, and says to himself I want to try it. Then he opens the game and is overwhelmed by game, he will quit and say something like: what a piece of trash is that, control is mess and there was no cool fantasy like the one in cinematic. I will go play my XYZ mobile game, that is fun from start.
This is the whole problem with RTS, they are just not fun and the fun comes after you mastered tens to hundreds different aspect of the games. To meet the fun that you are promised you have to learn the game, that’s fundamentally wrong.
AQ is an accessibility setting, it simplifies one aspect and makes it easier to get to promised fun element, building big base and clashing with large armies.
Do you realize how hard is multitasking ? or actually did you know that humans are almost incapable of consciously multitasking ? Multitasking is often just learned mechanical behavior without any real thinking involved (also often recognized as thing we should avoid, if we want to be really productive). Core requirement to play RTS well and have fun is to do one thing that is extremely hard to people to learn.
Also why would someone with AQ was less serious about the game, then the one without it ? they are both serious and want to win, if they queued into a multiplayer match. If anything making difference in rules between quick and ranked match, would actually finally help to distinguish and properly justify existence of different queues. One is more casual experience, other is full competitive experience like in tournaments.
You do realize that difficulty is just part of accessibility for a game ?
Accessibility means that game is approachable by more players, including players with handicaps or different preferences how to play.
Difficulty is just a slider, how hard the game is, or in our case how much would AI play effectively, or campaign AI spawn units.
Playing different difficulties with AQ and without AQ are different experiences. Yes in a way for some players AQ can enable them to play higher difficulty, but most of the time, that’s not true. Playing higher difficulty requires better understanding of the game.
On other hand experienced players, who have no problem with playing against hardest difficulty and can play without AQ might actually prefer to play with AQ, so they can play without pressure and take their time between actions, instead of constantly going back and forth to queue something, they already well know that they need in X amount…
In modern games accessibility is everything, and if hardcore RTS players do not want to understand that, then stop wanting more players in your games. If you can have one more accessibility setting, then you should have it.