>HTTP/2 protocol — a fundamental protocol that is critical to how the Internet and all websites work

No, it isn't. This whole article seems more like a marketing sales pitch than a disclosure.

I visited a few common sites and they seem to use HTTP/2. I'm not sure the point of arguing it's not fundamental, a cursory glance shows HTTP/1 is bottlenecked by not being able to use the same TCP connection to serve multiple resources (something HTTP/2 fixes)? Is there ire against HTTP/2 adoption, and for what reasons?
I'm not an area expert, but common issues raised over the years:

- HTTP/2 as implemented by browsers requires HTTPS, and some people don't like HTTPS.

- HTTP/2 was "designed by a committee" and has: a lot of features and complexity; most of those features were never implemented by most of the servers/clients; most of those advanced features that were implemented were very naive "checkbox implementations" and/or buggy [0]; some were implemented and then turned out to be more harmful than useful, and got dropped (HTTP/2 push in browsers [1]) etc.

[0] https://github.com/andydavies/http2-prioritization-issues

[1] https://developer.chrome.com/blog/removing-push