@tomsssss87 I think this would be battling with consequences not the cause.
What are the two main causes of smurffing:
1 - Diamond lobbies are too hard, people don't like to grind, so they create new profiles
2 - people want to play with lower ranked friends time to time
Next most popular cause is "I did not get heirloom on my main" :D
Introducing above mentioned limitations would only create additional issues:
a) players would be forced to pay for the account = limit new player base, ease of entry
b) question of security = how safe would you be to give Apex your phone number? I would probably opt out even if that would mean uninstalling the game to be honest, other option - e.g. in my country you can get prepaid card for <1 EUR with a new number, I could just buy those in bulk and smurf away, sell them to someone same as people now sell accounts boosts and other stuff related to smurffing
c) IP control - impossible for people with changing IP as well as unfair for people who have ISP with limited range of IPs that are changing = you might run into someone else in your network who registered his account with this IP before you got the IP
etc.
Matchmaking fix and better/faster banning reaction time is so much more efficient solution here. As for people who can't play with their friends - well enjoy pubs or teach friends to be better in Apex, end of story.