[SturgeonsLaw]

It doesn't require one from a technical perspective as you've pointed out, but every business incentive is to lock people in to accounts. It makes it easy to collect data on the users, to enforce payment by locking accounts, etc.

I too prefer offline-first tools, but the market doesn't, and people are trained to sign up with an email account and password so for the masses "this is just how it is".

I don't want to be a pessimist, but examples of user respecting systems are mainly commonplace in certain corners of the highly technical FLOSS world, it's certainly not the experience of the average person.

TOTP being a notable exception.