As the article points out, it's not really fair to criticize SAML for not using JSON, given that JSON barely existed at the time.

If you needed a serialized representation of structured data, I think it made engineering sense to use XML even if it was more featureful than you needed. The alternatives were ASN.1 or rolling your own format from scratch. It's not at all obvious that those are better.

(You could argue in favor of rolling your own format on the grounds that it wouldn't be vulnerable to XML-specific security problems, but I don't think those problems were fully appreciated at the time. If they had been, probably people would have come up with some kind of quasi-standardizable secure XML variant that just disables the specific features that cause those problems.)

I agree that XML (even without the security-relevant misfeatures) is worse than JSON or other non-markup-language serialization formats for the majority of use cases that don't need a markup language, but this is not a big problem, it's basically just syntax.

OpenID Connect actually has all the machinery needed to support federated login as part of its dynamic discovery and dynamic registration specifications. The issue is that absolutely no one uses them or implements them.

Smaller tech companies don't want federated login to happen. They are, as a rule, far to happy to rely on the SSO tax to up-sell enterprise customers. The major authentication companies don't want federated login to happy because it invites more competitors and threatens their absurd margins.

Until someone manages to solve the business side, no amount of improved technology will change a thing. I'm pretty sure the few small interoperability gaps OpenID Connect has could be corrected in a matter of months if the stakeholders actually cared.

> I should be able to create an account and log in just about anywhere using a backend I control. It can be done, but not with what we have today

IndieAuth exists, it's just not widely supported.

The real problem is that they used eXtensible Markup Language but invented their own inner extensibility syntax on top of a language where this was already a core feature! It’s the first word in the name!

It’s like “using JSON” but actually encoding objects indirectly through your own made up object notation… that is structured.

That's what the original OpenID (from back in the LiveJournal days) was supposed to be right?

"Host your own identity"