Ummm... Excuse me? o.O
If anything, you should get Lower Priority Queue first. But even before that, you'll be given a chance.
I've had to leave a number of games but personally, not a single time-ban. Just annoying LPQ @~@
If this really happened to you then I'm not sure how. You should really check it with Riot Support.
This isn't baseball where 3 strikes you're out >.<
If you've decided not to touch LoL then that's your choice. Many games to play anyways, hope you find them fun ^~^
But since this is an Overwatch thread.
I finished by placements 5 - 5 again . _ . and have landed it silver.
Guess I'll have to embrace my inner Genji to get to Gold or at least enjoy it here >.<