Valve posted their recent thoughts about Dota 2's problematic players in a wall of text otherwise aimed at the upcoming matchmaking changes. They made it clear such players are unwanted and are receiving hilarious 19-year long bans.
Dota 2 is one of the most popular and most competitive games around. As such, it is a magnet for players who desperately want to climb the ranks but tend to blame their teammates rather than examine their own mistakes and improve upon them. While this is not the only reason why people like to be toxic in online games, it is certainly one of the most if not the most represented one.
Valve have had enough of trying to correct their behaviour apparently, as a recent blog post regarding matchmaking took a look at the not-so-correctional measures that are now in place to prevent such behaviour. They "a few different ban waves for bad actors" with the first ban wave reserved for "exceptionally low behaviour scores".
For those not familiar with the way Dota 2 handles things, Valve have a system called Behaviour Score, with the community often referring to it as Conduct Score. It can range from one to 10,000 and the score often depends on how teammates perceive a certain individual. For example, getting Commended by teammates will increase the score while leaving games and getting reported will reduce it.
Therefore, those with low score are the unsavoury types that everyone would rather avoid as a teammate. As Valve put it, "users that reach this low level of behaviour in the game are too big of a tax on the rest of the community and are not wanted". This manifested in with the users being surprised at the outcome.
In the case of the person who made the linked Reddit post, their Conduct Score was 509 at the time of writing but given the ban was in effect, it's hard to imagine it going up or down. To put things into perspective, this person's behaviour earned them only 509 points out of possible 10,000 which hints at both toxicity and potential exploitation of in-game bugs.
Speaking of which, Valve's post announced that exploiters would also get hit during the ban wave, along with those who purchase accounts. Just to make sure they are not coming back, Valve are blacklisting phone numbers associated with said accounts so they can't just make a dummy and play on it. They will have to get a new phone number to do so.