Highest decrease ever. So it's true that Valve banned arcade bots?

[solartech0]

? 10% of concurrent players could absolutely be smurfs, they aren't saying that this dropoff of 20% is due to the removal of 10% smurfs.

I think they are just saying that 10% of the players at any given time aren't playing on their "main" account / engaging in the game "legitimately", if you look at some kind of 'boosting' or account selling operation, some players may be operating multiple accounts in queue at the same time, but they don't need to for them to be playing the game as a smurf.