>modern HTTP/2 has everything it needs
Except for speed, weight and practically unusable in any not resource-based networks without knowing beforehand what resource you need.
It's not even suitable for web as in 2021 there are still no agreement on how “real” REST interfaces should look like to not be shitty.
And that's totally HTTP fault as URL/URI is the reason we can't normally identify different kinds of objects and actions upon them.
And that's totally HTTP fault as there are only 8 strictly defined METHODS we can use, and they are pretty shitty in terms of extensibility tbh.