Chris Espinosa has a solid framing on internet communication protocols.

There are four great modalities on the Internet:

• pushed static pages (email)
• pulled dynamic pages (hypertext)
• 1-to-few short form (messaging)
• many-to-many short form (social media)

The first three started out as isolated, competing proprietary systems. Remember PROFS and Minitel and AIM? They all hit an inflection point where the common standards became as good as vendor features, and interoperability became more important than vendor lock in.

Threads federating is the last point.