Let me guess, you are on console? Sorry but aim assist is not going to make people play well. There is a massive difference in aiming skill even between people using MK.
Now, that is not why people turn off cross play, more so if he is a predator, he wants easy games, that is why he turns off crossplay since by far PS players are casuals.
People are not going to grow a brain with training, most are not even going to do it. This game would have needed skill based matchmaking but now its to late, not enough of a player base. I wonder how many people even played the predator training thing. I bet not many. I will say this, I had many instances when people knew enghlish, I told them to stick close, they did not care, left for veritanium and got killed.