SMS 2FA does more than provide extra security for your account. Perhaps more importantly to companies like Facebook and Google it also makes it much harder for spammers and bots to register accounts. At the very least it adds the expense of buying a SIM so you can use the number just once.
Risky if you're planning to use that SIM to prove that you're a legitimate person to a data mining company like Facebook or Google. That SIM gets reported stolen and your account could go up in flames, which is a big problem if you've been spending weeks grooming it to look real.
