The strength of open protocols is interoperability, and the "simpler" the protocol the better (SMTP, HTTP, matrix, etc.)

The downfall of open protocols is ossification through widespread adoption, then inflexibility by assigning its maintenance to a committee then deification of the institution that was entrusted with its maintenance (run by self important PhDs that lack approachability and are also not competent to make changes yet maintain the simplistic vision laid out in the original architecture.)

We have also seen open and interoperable protocols transition to closed and proprietary systems, this might be the most common outcome (such as Signal's use of XMPP but lack of federation, and Microsoft's inability to publish its document formats.)

In any case, none of this is good or bad, its only important to keep the protocol as interoperable as possible yet flexible as long as possible while maintaining the original vision that made it a success in the first place.