[jlokier]

That's because "Web 3" is more of a marketing term, whereas "Web 2.0" was a descriptive term coined for something that had already emerged in the preceding years from countless independent implementations, evolving together.

When "Web 2.0" was named, most of the techniques had been used for over a decade, and social networking side of it was well established too. Even "AJAX" was coined years after some sites were already using that technique, without that name.

Web 3 is an attempt to portray p2p, cryptocurrency, IPFS and similar types of networks as on an equal footing to the evolutionary changes that vaguely made up Web 2.0.

In particular, the name implies it's "the" (singular) next version of the Web after 2.0.

But it's too early to be sure of that. Most people aren't using it, most sites aren't using it either and don't plan to. The real successor to Web 2.0 that things evolve to en masse might be quite different than Web 3 proponents are describing at the moment.