Maybe I'm misunderstanding something but quic has been really great to work with and solved a lot of problems in places other than http for me personally
I'm not saying HTTP/3 is bad for the type of things people get paid to do. I'm saying it's bad for the type of things people chose to do without being paid. For example, it's impossible to connect to a website with HTTP/3 that does not have a CA TLS cert (and all HTTP/3 libs in major browsers are compiled with self-signing disabled). That means it's impossible to host a visitable website (by random people) without getting the continued permission from a third party corporation (there are no CAs included in browsers that are run by human persons, there are only corporate and government CAs).
This is extremely sensible for for-profit corporation and institutional practices. But it makes hosting a website from home far, far more complex, fragile and gives all websites a very short lifetime (just months) without continued active mantainence. Normal HTTP+HTTPS websites are visitable forever without doing anything. And that's ignoring the problems of CA centralization and censorship. Having to ask permission from a corporation to host a website is absurd. It is not required in HTTP/1.1 or HTTP/2.
HTTP+HTTPS is the most robust and accepted solution to CA TLS problems but HTTP/3 doesn't allow it.