prepaid sims for a phone cost 3 dollars here in brazil so it’s not that huge of a task, a dedicated troll will pay that just to ruin people’s games
then theres the problem of online phone services that you pay like 5 dollars for and get 5 phone numbers which can be checked online without a phone (and can also receive voice mails or texts from things like google or blizzard)
i liked the idea of a mobile authenticator more, it’s tied to 1 phone hardware, trolls usually wont pay to buy more used phones or new phones just to keep trolling, it gets expensive