My guess as someone who's been in a position to implement it a few times but haven't gotten to:
- "Upstream" Support, For various combinations of stacks I've worked on, there has always been one component that didn't support it cleanly, (Flutter x Ory was my last attempt for example). If it was as easy as "just" enabling it I'm sure it'd be more popular, but when your provider or tech stack doesn't support it out of the box it's usually not worth the effort to implement it from scratch.
- Customer support. This has many sub problems. At my current job, customers get confused between social login and email/password all the time. Adding a newer more complicated technology would be a recipe for disaster.
Similarly, because my job deals with money in a country where mobile theft is fairly rampant, the additional burden of trying to reassociate a users public key/account/device is problematic.
Finally, I think the concept of managing private keys for a user is fairly complicated, though with passkeys and google/apple syncing your private keys for you I hope to see this burden fall away, and with it the rise of webauthn
(Going from memory) we used firebase and had access to the native authentication SDKs, then we we switched to ory, we had to hack it back in because the documented way to implement ory would have used browser authentication.
Ory provides a javascript bundle you load to do webauthn, which (again IIRC) didn't work inside the browser inside the app, and although we figured out some workarounds, would have conflicted with how we implemented the native auth.
- "Upstream" Support, For various combinations of stacks I've worked on, there has always been one component that didn't support it cleanly, (Flutter x Ory was my last attempt for example). If it was as easy as "just" enabling it I'm sure it'd be more popular, but when your provider or tech stack doesn't support it out of the box it's usually not worth the effort to implement it from scratch.
- Customer support. This has many sub problems. At my current job, customers get confused between social login and email/password all the time. Adding a newer more complicated technology would be a recipe for disaster.
Similarly, because my job deals with money in a country where mobile theft is fairly rampant, the additional burden of trying to reassociate a users public key/account/device is problematic.
Finally, I think the concept of managing private keys for a user is fairly complicated, though with passkeys and google/apple syncing your private keys for you I hope to see this burden fall away, and with it the rise of webauthn