If I just lost a game with someone

The problem is not that you get matched whith them again, it's your bias toward them and theyr bias toward you. Anyone can have a bad game and as far as you know, that 0/20 fizz of the last game who is now playing Vayne (his main) might be hardcarrying your whole team with a score of 12/1 this time or something along those lines. No matter if you know someone from previous matches never go into a new match with last match's bias: last match's problems are over with last match's end-game lobby, even if you both flamed the shit out of each other you gotta try and start anew if you find him again because as far as you know if he's in your elo (and so in your queue) he at least deserves that elo (maybe rank more, rank less, there's not really a difference between say plat 4 and plat 3 or bronze 2 and bronze 1) meaning that if he played badly last game he probably either had a bad game or was forced on a role he wasn't good on or picked a champ he's not too good with.

So Tl;dr never bring problems from a match to your next ones, it's bad for both you and for your team.

This would make matchmaking in d2+ nearly impossible, sorry pal but just accept that everyone loses and there's no reason to immediately assume you'll lose again.

Even worse when you mute/block/report and STILL get them again, I had that happen 3 times in a row.