"that library needs a different code block for every one of those methods"
Yes, and that is trusted code - even with isolation, an compromise of that method's resolution code would result in malicious parties being able to impersonate anyone else using that method.
There are use cases where you don't want correlation, in which case the decentralized identifier might exist only for you to log into a single web site. At that point, it might be easier to use a method like did:key or did:jwk which encode all of their information into the URL itself, and forego the ability to rotate or revoke keys.
Yes, and that is trusted code - even with isolation, an compromise of that method's resolution code would result in malicious parties being able to impersonate anyone else using that method.
There are use cases where you don't want correlation, in which case the decentralized identifier might exist only for you to log into a single web site. At that point, it might be easier to use a method like did:key or did:jwk which encode all of their information into the URL itself, and forego the ability to rotate or revoke keys.