QUIC is really cool technology. It can solve a wide range of problems that aren't necessarily HTTP based.
However, HTTP/3 is using QUIC as a patch over badly designed websites and services.
QUIC doesn't solve the problem, it provides another path around the source of the problems. This blog was written by Akamai, a CDN that makes profits off the problem of "my website is too fat to lose quickly anymore". I don't blame them, they should sezie the opportunity when they can, but their view is obviously biased.
QUIC makes most sense for sites that can optimise it, like the Googles, Cloudflares, and Akamais of the world. For the average website, it's just another technology decision you now need to make when setting up a website.