Valve has introduced a new system which aims to remove smurfs
“Players using multiple accounts create a negative matchmaking experience at all skill brackets, so our goal is to add just enough friction to this process that the number of players doing this will be noticeably reduced. Having more players using their primary accounts will have a positive effect on both Ranked and Unranked Matchmaking.”
The new system will require you to link a phone number to everyone Dota 2 account you have. While they not force you to do this, you will be unable to play ranked / competitive queue without the use of a phone number. By doing do, smurf accounts will be removed as only one phone number can be linked to each account. While this may not remove all smurfs, since many people do have access to more than a single phone, it will definitely limit the number of smurfs overall. Note that this new system will only remove smurfs in ranked matches, as it only requires players to link their phone number if they wish to play competitively.
Valve has given a 2 week period for everyone to hop on the new system before they stop an unlinked account from playing competitively. This means after May the 4th, you will be UNABLE to play RANKED if a phone number has not been linked and confirmed. The change is extremely interesting, as it physically prevents you from entering ranked matches with little way to bypass the system.
This new change is great! I really hope other games such as cs.go, Overwatch and LoL adopt this system too, since it reduces the ability of payed boosters to hop on an account and carry out their services. Overall, this will definitely be a positive change in the Dota 2 competitive community .