To OP: it does add significant block to spammers so they may only create 5,000 accounts slowly instead of millions of accounts quickly.
Most email services require a phone number or other email service to sign up if there is anything fishy about your connection/browser, and there can be hundreds of things, even just some specific browser extension installed, or you using the same mobile network IP as a spammer.
And there are services where you can buy a real temporary 4G/5G number (non-VoIP) for a service for less than a dollar per use. Once a number has been used for that service it still has every other X number (thousands) of services it can be used for before it’s retired from the pool. But that does add up after a while if you’re making tens or hundreds of thousands of accounts.
To OP: it does add significant block to spammers so they may only create 5,000 accounts slowly instead of millions of accounts quickly.
Most email services require a phone number or other email service to sign up if there is anything fishy about your connection/browser, and there can be hundreds of things, even just some specific browser extension installed, or you using the same mobile network IP as a spammer.
And there are services where you can buy a real temporary 4G/5G number (non-VoIP) for a service for less than a dollar per use. Once a number has been used for that service it still has every other X number (thousands) of services it can be used for before it’s retired from the pool. But that does add up after a while if you’re making tens or hundreds of thousands of accounts.