> > mostly for accessing legacy sites that were around at that time.

So change the email address on those accounts?

That's not always possible.

Email was often used as a primary key on older websites

Originally websites had usernames and passwords. Username was used as a primary key (such as this website).

Using the email address directly as the username/key is a more modern trend (mid-late 00s). I believe this coincided with the dominance of gmail where people would have a forever email address. Before that, your email address would regularly change if you moved ISPs/schools/jobs so it wasn't a good identifier.

Recently i found that several services I “signed into with Google” allow neither converting to a password nor binding to a different Google account. B2b SaaS apps in fact.

Yes, and it's possible to change that e-mail. The only place I've encountered which doesn't is Alibaba.

ChatGPT is another.

Bambu Labs online account has the same restriction for some reason as I found out the hard way, though I had thought that was extremely rare.

Wow way to miss the point

> My domain registration is just over 25 years old... I guess I'm also "legacy"?

Mine too -- I mean, I had domains in 1994-1995.

Most people who have legacy AOL emails have them from more than 25 years ago-- indeed AOL was in decline by 2000.

And "protip: go back in time 30 years ago and tell your kid self how to get a domain name, and navigate internic's overcharging" isn't quite as practical to implement.

A lot of these old services used the email address as the fixed user identifier making it much less likely (certainly for those bucket of services) that he'd have a user-facing option of changing it.

Any recommendations on registrars?