Skill-based matchmaking.

The reason you run into people with ridiculous psn names is because of the number of people who run RTG accounts along with their main, most streamers have multiple accounts for such things so it's likely the people that follow them do aswell. Personally I'm happy just playing with one account, but some people run 2 or 3 accounts.

On another note my best result in recent years is Div1, but I'm stuck in the middle of div 5 right now and don't know why. It might be because I'm not running the ultra sweaty formations with the ultra sweaty players. I'm just chilling this year though, and I've already taken a month and a half off. I only came back a few days ago, but I breezed through the lower divisions to get to my current one. 

I don't know if other people are like me and possibly took time to play other games and came back or not, but I would suspect that and RTG accounts are why you run into so many sweats all the time these days. There is also the possibility that the seasonal rests have dropped some people back down a couple of divs. That's the reason why when I first came back on I was div 8, this season it didn't reset me and I think that just because I had only barely hit div 5 before the reset. 

RIVALS matchmaking isn't based on DIVISIONS but on SKILLS!
That is, if you've always played in D1, you'll continue to play with players of that level even in lower divisions...
It seems absurd, but from what I understand, that's how it works!

I can’t agree based on my own experiences. If that was the case I would have been able to get to div 5 without batting an eyelid. It was easy, like it is every year when I finally start playing, and I guarantee I could go do the same thing in seasons. By your logic I should only be facing people of a div 1 and div 2 level of skill, but I'm not always. I've not played a game of seasons yet this year and used to consistently play around the div 1 and 2 mark in seasons, but I can almost guarantee I could walk my way to div 5 with barely a challenge. In fact the only challenge would be people like me starting it late, or actual smurf accounts. 

It's likely that their is some sort of matchmaking involved yes, but it's nowhere near as Powerful as you seem to think. The main problem in these games is it takes a while for divisions to settle, especially with people running rtg accounts. Heck I wouldn't be surprised if some people set up an account to play in lower divisions, "so that they don't have to sweat so much all the time" would probably be their reasoning. 

Once you hit your level in a game it always feels like a sweat fest, once you are surrounded by people your level or better the game will always feel harder. Their isn't really much they can do there, but hopefully they can at least protect the lower skill players from people abusing the system.

That's it!!! I think they've changed the matchmaking to that and it's a huge mistake, just another way to ruin the game.