TOR+SMS verification or is there anonymity on the legal Internet?

Question

Anonymity

Today I tried to register through TOR on some resources: yandex, FB, Google, Rambler.
Of all, only Yandex did not interrupt registration when refusing to enter a phone number. The rest require SMS verification, which in itself nullifies any attempt to be anonymous. There is another problem that popular SMS-gates are banned: you cannot anonymously buy a number for yourself, receive SMS and leave it.
Thus, anonymity becomes a presumption of guilt, and anonymity cannot exist on large sites. How can this be done legally?