Today, we permanently banned 90,000 smurf accounts that have been active over the last few months. Smurf accounts are alternate accounts used by players to avoid playing at the correct MMR, to abandon games, to cheat, to grief, or to otherwise be toxic without consequence. Additionally, we have traced every single one of these smurf accounts back to its main account.
You’d be surprised at how hard people will circumvent that logic
Some people literally don’t even believe themselves after admitting to smurf. Eg: https://old.reddit.com/r/DotA2/comments/167e3ne/i_got_vac_smurfing_ban/
People are shit.