Most users don't have a credit card - they're not all in the USA. A big chunk don't even have bank accounts at all.
However that's basically what phone verification does. In case of suspicion someone has to provide their mobile phone number. It's texted with a code and a counter increased. The same number can't be used over and over. Unlike credit cards, the assumption of universal mobile phone access (amongst people who have internet access) is very strong. It works very well. In this case, the account was shut down without this being possible, which is only used normally for very clear cut cases. Don't assume the full story is public.
However that's basically what phone verification does. In case of suspicion someone has to provide their mobile phone number. It's texted with a code and a counter increased. The same number can't be used over and over. Unlike credit cards, the assumption of universal mobile phone access (amongst people who have internet access) is very strong. It works very well. In this case, the account was shut down without this being possible, which is only used normally for very clear cut cases. Don't assume the full story is public.