I think there's been a huge misconception of what MCP was meant to be in the first place. It is not a transport protocol, and it is not (primarily) designed as a remote RPC server. It is really meant to be a local first means of attaching tooling to an LLM process. The use case of "centralized server that multiple agents connect to" is really only incidental, and I think they honestly made a mistake by including SSE as a transport, as it has confused people to thinking these things need to be hosted somewhere like an API endpoint.