It’s a meaningless term for web developers, just as Web 2.0 was. It’s supposed to mean decentralized services and it was sort of hijacked by crypto companies for marketing purposes. Blockchain isn’t a particularly useful technology outside of its niches of cryptocurrency and gimmicks (like NFTs or whatever) and isn’t used by 99% of web projects. (There’s no Google, Apple, Microsoft, etc. blockchain, after all.)

I’ve been a web dev for decades now and to me, Web 1.0 was basically the era when people posted their own content on their own web sites. Web 2.0 was a marketing term used by social media companies to describe a new era where even non-tech savvy users could post content on MySpace, LiveJournal, Facebook, etc. There was no major tech advancement. Web 3.0 is supposed to be an era where even average users can take advantage of decentralized services. Again, nothing major tech-wise.

In terms of actual technology, there’s been significant shifts like CSS 3, HTML 5, ECMAScript 6 (JavaScript’s standard, which has evolved a lot recently) and others. Server-side web tech has also changed a lot over the years. Most web sites probably still use PHP — Wordpress is surprisingly ubiquitous — but NodeJS, Ruby, Python, and other languages have had major advancements. Those (and several others) are the ones actual web developers cared about.

TL/DR: Web 1.0, 2.0, and 3.0 are just marketing terms with vague meanings to describe shifts in web culture, not web technology.