Tl; dr Behavior score actually works pretty well and most people don't realise how important it is.
So I've always been playing with 10k behaviour score. Most of my friends also have 10k, sometimes we drop to 9.8 after a few reports but it goes back up very fast. Due to the lack of players in 6/7k bracket we often get 'varied behaviour score' and those games are sometimes worse than usual but there is not a huge difference. That's what I knew about behaviour score before.
But oh boy when I started looking for people to party up and play with. I tried playing with some people who's beh. score was 2-3k.
- We actually couldn't find a game. It takes 20 minutes for a low behaviour party to just find a game in 6k (all roles selected).
- And the games are trash. Everybody is muted, toxic or legit throwing. I was lucky that the enemies were throwing more that us and we actually won all games, but those games were still bad.
- We played only a few games and all of them were ruined. There was a safelane storm who got fucked in lane and went jungle at min 3.
- Ranks are very unbalanced. Since there aren't that many sub 3k beh. score players – they just put a lot of ranks together. I played with so many divine 2-3. I normally would never get a divine in my games.
- One guy just took my role. He wasn't toxic. He never said or typed anything. I was happy to give up my role anyway (so that he can lane with his mate). But he just ignored the assigned roles, that was fucking weird.
- In most games everyone was extremely quiet all game. But there was always someone to start screaming at everyone at the end because we couldn't end quick enough. (to be fair that was my party teammate some times lol)
We actually tried to play more but had to give up after queueing for 15 mins.
I am very confused of why there are so many, otherwise normal people, who have such a low beh. score. It is actually somewhat hard to find teammates with 10k.
So yeah be grateful for all the weird toxic players that are 'locked away' there. And that was party queue. Imagine what is happening in solo.
Source: https://www.reddit.com/r/DotA2/comments/tmmn4n/behaviour_score_appreciation_post/