Makes me want to unplug and go back to offline social media. That's a joke. The dominant effect was networked applications getting developed, enabling community, not a shift back to client terminals.
Web2.0 discarded the protocol approach and turned your computer into a thin client that does little more than render webapps that require you to be permanently online.
There was also FidoNet with offline message readers.
People must have been pretty smart back then. They had to know to hang up the phone to check for new messages.