REST is more advanced than RPC and more compliant with the principle in computer science of avoiding the necessity of codecs to view the transit of information

you have headers (request and response), parameters, paths, body (request and response) and cookies, with RPC you only have request and response

you didn't even use a normal RPC layout for NIP-01, with ambiguous method names in the messages, as well, that makes it more complex to write codecs for it

and subscriptions can be done on HTTP since about 2016, called Server Sent Events SSE

i learned all of that stuff in the last few months because i'm doing this for my paid gig, and it's extremely standardised such that there is no such thing as a HTTP framework on any programming language that doesn't support everything already out of the box

meanwhile, here with nostr we have number codes, ambiguous message formats, absurdly complex filter tag parameters (for most languages you have to do omitempty with all all letters of the alphabet in both cases, which you put an unnecessary # prefix on when there is no other single letter fields in the object), and the lifecycle of connections is very complicated and wastes huge amounts of code and network resources to keep alive, when you could have done that with SSE