Bad Matchmaking system?

Does anyone else think the matchmaking system is a little messed up when It comes to ranked play? I’m a platinum 3 and at the end of most of my arena games when I check the stats, it seems there is usually an onyx or high diamond player/players in my game. I feel like a player who is ranked platinum should never see onyx players, and rarely see if not at all see higher diamond players. I also see alot of games where there are people from gold, platinum, diamond, and onyx all in the same game. How does that happen? How can you have 4 different rank tiers playing in the same game? Anybody else having these problems or seeing mismatched games? Or am I just getting really unlucky with the system?

the thing is that there’s probably low population and sometimes they are in the same fireteam. Like an example I’m platinum 4 and my friends are gold 1 but we love to play together so we get matched with all kinds of ranks.