i may be wrong here, but if i remember correctly, in ech, essentially our first communication is done with some central server (which as of now is mostly cloudflare) and then they make some connection with target server, and then a channel is established between us and target. my google-fu brought me this , which is basically this only

https://cf-assets.www.cloudflare.com/zkvhlag99gkb/3C9ceBTx5AQXu8tS0lgzdF/55ea89f5a56843db15296b2b47f7b1c2/image3-17.png (https://blog.cloudflare.com/encrypted-client-hello/)

I am unfamiliar with QUIC, and quick search basically tells it is kinda like multilane highway for udp.

If I have to compare, (not a network engineer or a person who has studied networking, to me anything beyond the simple protocols seems magic), QUIC seems like a techt which is only used after you have made connection with target, so its implementation is google independent (they seem to be lead developers for this). Whereas in ECH, cloudflare are the primary devs, but also the holder for the public keys (someone else can also be the holder, but i dont know of any other provider currently, maybe my lack of knowledge here)

Essentially just an extension of your point that implementation is lacking

for me, currently the problem is over reliance on Cloudflare, which is yet another big tech company

it maybe, but i dont think so, most animals dont go out of their ways to breed with same species from far off, especially if the said species forms communities. I think the simpler logic is - boredom - the people you grow up watching everyday become the normal, and if someone new comes, you curiosity gets to it