> you’re just using HTTP as a substrate for some other protocol, in which case you might as well just open a port and serve that protocol directly and not pretend to be HTTP.
Browser does not allow to access any ports with any protocols.
Often intermediate software gets in the way as well. For example with Kubernetes it's trivial to expose HTTP service using Ingress and it's not trivial to expose other protocols.
Another HTTP plus is that it's trivially secured by TLS and every developer knows API for that. Using TLS for your own protocol or QUIC is absolutely not trivial and probably more like arcane knowledge.
Browser does not allow to access any ports with any protocols.
Often intermediate software gets in the way as well. For example with Kubernetes it's trivial to expose HTTP service using Ingress and it's not trivial to expose other protocols.
Another HTTP plus is that it's trivially secured by TLS and every developer knows API for that. Using TLS for your own protocol or QUIC is absolutely not trivial and probably more like arcane knowledge.