2FA will definitely do something. There are more ways to do it than just with a phone number. Could be an authenticator or so on. The fact that some people will get through isn't a reason not to try. Or do you feel that way about cheaters too? "Oh some of them can still cheat so might as well let them all cheat as much as they want" is a crappy view to take. If you want to cheat by using all your family's phone numbers, go for it. I hope it gets you banned.
You can use phone numbers, but hopefully as people report you, your extra accounts would all get banned, winnowing it down until everyone just has one account, as it should be. Ah, how lovely that would be.
Lots of things can be done to stop smurfs, and they should be done. Smurfing removes any ability for the SBMM to do its job properly, and it's absolutely ruining my game experiences. I'll keep talking about it until I get frustrated enough to quit the game entirely, which is slowly creeping up to be more and more likely, or Respawn does something to get rid of all the crappy cheating smurfs out there.
