Yes, so if law enforcement (for example) were trying to find out the phone number for a Gmail account, they would then have to go to Burner or Twilio to get records for the Burner phone number account. I guess it depend on what level of anonymity or privacy you're going for.

Wait, does Gmail ask for a phone number when signing up these days?

It did sometimes. I think a cookie/IP limit kicked after it detected "you" had created a few accounts.

It is extremely easy to create an anonymous number already, let alone a gmail account. A friend of a friend daisy chains anonymous numbers with physical burners for a "proxy" effect.