Network management is there for a purpose, and the people focusing on bypassing it are generally bad actors. The authors of HTTP/2 and HTTP/3 are more focused on guaranteeing delivery of ads than being able to block malicious activity.
I fully support user choice to disable whatever protocol they want. I also think modern browsers lack options in this department. If you dislike QUIC, which I can completely understand, you should disable it.
On the server side, though, you can use modern servers and tell all your clients to stick with HTTP 1.1. Let the people who do like QUIC (or don't care) get the benefit of faster page loads and lower latency. HTTP/2 and HTTP/3 solve some real performance issues, particularly for users with unstable or slow internet connections. I don't see why would would deprive them of that simply because you prefer to have the protocol disabled.
But networks often block them for security reasons, and it's their network and prerogative to do it as a condition to use the network.
I don't follow your reasoning. So you have the ability to block QUIC, but declare QUIC to be a "bad actor" trying to bypass your network management?
They switched from TCP to QUIC base, what can be done over HTTP3 can also be done over HTTP2.
From the POV of the network it is much more similar to a UDP VPN than to HTTPS over TCP