Could someone explain matchmaking to me a bit? Cause I don't get it.

The title kind of speaks for itself. I've put a lot of time and hours into this game. I have never really been a big fan of ranked and have always sat around a silver ranked elo because I simply don't care to put time into climbing. I don't like the idea of if I want to be viewed as "better", I better hope my team isn't terrible where every lane loses hard besides my own if I'm playing well.

But anyhow, not the point. So in normal games I have approximately 6.5k games played give or take a few. I often feel the quality of my normal games are bad. In particular, I've been playing some top lane just to change it up and I swear I have to give one of my kidneys just to have a quality game. I don't need to totally dump on my matchup. I just want the rest of my team not to lose for me by soft inting making it miserable to play out the match.

Now what I'm trying to get at is the teams more often than not feel unbalanced and unfair. So how exactly does the matchmaking algorithm work? I've noticed much higher elo players in my games, and quite honestly I don't want them there. I want to play with players my skill level. My previous game in particular there was a one trick Fiora with 1mil+ mastery points who was D3 last season (something along the lines of plat now). Obviously far beyond my perceived skill level. And that is kind of the root to this question. At the bare minimum how come I did not have a random somewhere on my team with the same perceived skill level to balance the equation? Long story short, this Fiora proceeded to absolutely dumpster my team (for the most part) creating quite the non-fun experience.

Why was this Fiora in my game? It doesn't matter who they were playing, it's just an example and refers more to the "skill difference". Shouldn't they be matched with others like them in terms of skill? Perhaps because I have so many games played? Someone please explain. And obviously I assume they were pre-made with someone on the enemy team, but at the minimum why didn't I have more "skill" on my team to compensate?

Please keep in mind this isn't to debate my rank or skill. It's an honest question and applies whether you're in high diamond or iron. I'm just here for a fun experience. Not to get all sweaty. I'm not a superstar every game I play. And I'd post a bunch of screenshots so you could see my performance in recent games versus the rest of my teams' to further push my rant here but I feel most of you have experienced the same and its not necessary. Do it on your own time if you want.