Valve's been going pretty hard on Dota 2 this year, and the latest is targeting those who start fresh accounts in the free-to-play game so that they can play easy games and stomp rookies. Valve has also traced the accounts back to their main accounts, and says that from now on "a main account found associated with a smurf account could result in a wide range of punishments, from temporary adjustments to behavior scores to permanent account bans."
Smurf accounts, for those of you who don't know, are brand-new accounts used by experienced players to avoid playing at a proper matchmaking level—or to just cheat, grief, troll, and be broadly toxic without permanent consequence.
For many players in competitive, free-to-play games, and for mobas in particular, smurfing has been a huge problem. It's extremely frustrating to enjoy playing against people who're either profoundly more skilled than you or just there to make the game worse for everyone else.
This is the second big smash for Valve this year, having knocked out 40,000 accounts in a day for cheating earlier this year. To achieve that Valve laid a trap for using third-party software that accessed data not usually read by the game client: They made secret data that only the cheat software would read, then banned accounts that had read it.
"While the battle against cheaters and cheat developers often takes place in the shadows," said Valve at the time, it wanted "to make this example visible, and use it to make our position clear." I expect that's much the same motivation behind this particular smurfing ban wave. This definitely applies to pro players as well—in March, Valve banned an entire pro team for cheating.
Though it's a decade or so old, Dota 2 is still very much alive. Earlier this year it got a massive update that made the map 40% bigger alongside a slew of other updates and tweaks that we noted might as well make it Dota 3.