Because there is no SBMM and it's just random.
A level 500 and level 10 press play, it just pools them together, that being said take the ranks with a massive pinch of salt! It doesn't mean a single thing, boosts, bot farms, casual breakthrough etc is the vast majority of players over 200 I would say.
Unless they have no life, work, family and claim benefits to sit there 24/7 on the game then it's possible. I've seen level 20s beat level 150s. You are looking at the ranks the wrong way, rank doesn't mean skill, it has a lot of possibilities and options behind it.
Ignore the rank and just enjoy the game :) Think of this way, if you are say level 200 and ONLY partied with level 200s... It will be a sweaty lobby and not fun at all :) That's if the lobby would actually would with ranks all around the same levels in the same match :)
No, ranks should not be split because that makes SBMM and that's not wanted at all in this game. It's equal/random and fair, especially in multiplayer, level 1s with level 100s with level 20s, 70s, 200s all in the lobby working as a team.
Logically speaking rank is useless and doesn't mean a single thing :)
I hope this helps.
