W3 at its core is very simple. This simpleness gives large gaps of freedom in what two parties have to do for exchanging data, e.g. 27 years have passed between the birth of W3C and Webauthn.

>Or that there's no end of open protocols for interoperability?

There is a multitude of reasons why you have marvellous designs on websites but you can't name a mass-market search engine you can run outside of the browser on your local computer using on-line data. Sure there are some or you can nowadays assemble some software parts and build your own, but it isn't a thing, and there is a why.