As part of a revision of the matchmaking system, Dota 2 requires a unique phone number from May 4th, which is linked to the account. With this measure, the developers want to improve the ranking experience.
Like every FreeToPlay game, Dota 2 has so-called "Smurfs". Players who are much higher in the skill level play new accounts in order to then look good against significantly weaker players. For these mostly newer players, of course, the fun of the game is ruined and does not exactly offer the best conditions for a healthy growth of the player base.
Hopefully, this hustle and bustle will be severely restricted with the requirement that accounts who want to take part in ranked games have to be linked to a telephone number. It will never be completely abolished, but the hurdle for such jokers to constantly create new accounts, including phone numbers, is significantly higher.
Dota 2 - Solo Ranking
Another change comes with the reintroduction of the solo leaderboard, players can choose to only end up in matches with other solo players. And so don't run into premades.
Groups MMR
In addition, players whose solo MMR is higher than that of their group will now receive stronger opponents. Experience has shown that the game experience was very negative when a player is significantly stronger than everyone else in the match and it repeatedly led to arguments. Statistically, such imbalances evened out in the long run, but in the individual games it led to an extremely negative experience and will hopefully be weakened with this change.
There are also other changes for players who ended up in the low-priority queue due to negative behavior. In addition, you will now get a ban for ranked matches. Initially only for a few hours, later for repeated violations for up to 4 days. So if you consciously ruin matches to take away the fun from other players, you can soon rest on the bench.
Furthermore, the bot detection has been improved to discover and ban automated accounts faster.
Regional changes
Ranking games will be switched off in South Africa, India and Dubai for the time being. Since the necessary player base for balanced rankings is missing there at the moment. Due to the small number of players, it was easy to exploit the matchmaking system on this server.
You can find the detailed announcement on the official Dota 2 blog page.