However, Google tries _very hard_ to prevent people from e.g. creating a gmail account without a phone number. Try it if you don't believe me.
No doubt they're letting me through because some security heuristic says I'm a real human, and I'm sure they'd eventually make me provide a number if I continued using the account (this happened to me with my university G Suite account a couple years ago and I needed to contact my IT department to manually disable the phone challenge), but so far I can't see any evidence that they're doing anything unreasonable.
Perhaps they're requiring you to use a number because you've tested it a lot.
We all knew password, no problems at all. Now it mandates 2FA. And because they mandate it for Google Ads, now it's on for everything like Google Drive etc.
You might be surprised to learn that this is how it works for Google accounts: it is default-on but you can turn it off.
> If they at least would allow for a sufficient number of options. Like paper-tan (even self printed), yubikey or similar, second email address, an authenticator, ... but even big companies often only require a phone number.
You might be even more surprised to discover that all of these options are supported for Google accounts.