See Analyses of the ratings - Spotting the issues for more information and a much longer discussion about this topic.
There is definitely an issue with the calculation of the team ELO ratings, other than “people quitting”. After playing enough games, even average players get a 2K+ rating. In an Elo rating system, playing more games should not automatically lead to a higher rating. You see many players with a 1000-1200 1v1 rating and a 2K+ team rating nowadays. I’m over 2300 TG myself, just because I played many games, but I don’t consider myself an expert.
Team ratings are not representative of a team player’s skill anymore.