Whilst I agree that there is a big portion of players who unfortunately used a Cronus - to which I can only assume they lack skill - MOST legitimate console players are at a disadvantage when playing against PC players. Those on PC can use their wrist and arm to control the recoil, flick the mouse to turn quickly etc. Whilst console players are stuck using a thumb/finger on the analogue stick. So yes, aim-assist is there to help console players have some advantage against PC players who have other advantages .eg FPS, reactions (what I mentioned above about flicking the mouse etc), and/or it's easier to cheat on PC.
As for the Crossplay... it goes both ways... whilst you might run into Cronus players on console (which again, is frustrating), there is usually a PC players who's blantly cheating with the likes of wall hacks etc.
One last observation, and I'm not trying to be that guy, but when you say... "if you think there are more cheaters on PC, then you're wrong". The answer is YES, yes there is... They're have been a handful of crossplay games that when I've turned off crossplay, I've seen a big drop in obvious cheaters. Yes, the odd Cronus user still appears unfortunately, but at least I'm not getting laser beamed across the map through several walls. As I said just an observation with my gaming experience.
A prime example of this would be CoD (which I know their anti-cheat is abysmal), but they banned something like 50k cheaters a while back, the same day 50k new accounts were made. More than likely on PC because you don't need a subscription like gamepass/gold/ps+. Furthermore on PC you can apperantly buy accounts that have "stealth" cheats. I've seen countless videos on YouTube where cheaters have told players that's what they do.