https://www.smashingmagazine.com/2021/08/http3-core-concepts...> While TLS 1.3 can still run independently on top of TCP, QUIC instead sort of encapsulates TLS 1.3. Put differently, there is no way to use QUIC without TLS; QUIC (and, by extension, HTTP/3) is always fully encrypted.
Basically there is no HTTP/3 without a TLS certificate.
I'm not sure what "problems that might arise from centralization" might be. There are many different TLS certificate providers from different CA roots.
Is your gripe that you don't like TLS? Judging by how long the migration from TLS 1.1 to 1.2 took, I assume we're at least 10-15 years away from a world where everything is encrypted by default without backwards compatibility (if we ever get there at all).