As others in this thread have commented - there are scammer hubs where a single person controls hundreds if not thousands of phones at a time.

The people who this method is most hoping to stop are the least likely to be impacted by it in the long run.

This is the exact method used to secure iMessage against spam: secure attestation and ‘console’ bans of devices (reversible by iirc phoning support, indicating who you purchased the used device from, and providing an ID). But Google is trying to pull a Windows 11 “TPM or die” conversion on the public Internet via Recaptcha. Welcome to the attestation wars, unwitting websites :)