It smells like a made up buzz word that did not originate organically. Someone coined this termed and released a bunch of press releases to get it to catch on. I don't even know why people are giving it the time of day. It's someone's marketing speak and it smells awful.
And furthermore, decentralization is not new nor is it unique to the web, nor does this "web 3" garbage have anything to do with the web either. Web 2.0 was also buzzwordish but at least it was referring to a genuine paradigm shift in the way that websites work. The inclusion of the XHR request API in browsers and the birth of publicly available RESTful APIs that web-sites could consume which helped lead to the split between frontend and backend development as specialties that we see today (whether that's a good thing or not is another discussion).
"web 3" is just marketing PR garbage for "crypto is the next big thing ... somehow."