Absolutely, however a major problem occurs, and email is a great example of this. When there is a fundamental need to change the protocol for reasons of privacy, security, authentication, etc. It becomes almost impossible to do when it is as wide spread as email, or it takes a very very long time to spread enough.

When one person controls the whole system, it's easy to pivot rapidly. I guess that's another argument against having widely used protocols (even though I disagree with it.)