I just came across the 'rank 3 required for competitive play' and it seems kind of lame as I'm legendary eagle level, with shitloads of hours on almost all versions of CS including CS:GO... And no this does not filter out people who don't give a shit., if someone plays casual a lot they'll automatically get rank 3 at some point and that doesn't mean they suddenly care about competitive and not start trolling.
I still feel like if a filter needs to be in place, it shouldn't be possible to buy the missions to XP boost past it quickly. That seems odd since there's no filter on whether those who buy missions are actually good/serious.
In my first 6 competitive matches since reaching level 3, at least 3 of those games have had someone grief TK and/or abandon the game if my memory serves me correct.
1. One person begged us to kick him because he didn't want to win. Our team was winning easily, and we never kicked him (I've been told that kicking may give you a cooldown, and they may have been trying to avoid some penalty). I think they started trying to block doorways and shot me a few times, TK'ing me at least once. We won the match, and they didn't TK enough to get autokicked.
2. Someone TK'd one of my teammates and left -- at least we got a bot. I think it popped up a 24 hour ban for them.
3. Someone on the other team abandoned the game -- first place on the scoreboard but the team was losing. I think we got a message about a 30-minute penalty for them doing this.