Ummm that's super random! Were you able to report it ok? Sounds like a bug more than anything else!

they could've been either AFK, queue dodging, and other stuff that might've caused that.

Same here, haven't played in months , come back and I am locked out of the game?
What sort of video game doesn't let you play?

This game is broken garbage.
That is why.
The devs are more concerned about making the trash can pieces of shit that throw rounds happy, rather than their actual fan base who spend money on the game