They didn't reinvent it, it's literally using JSONRPC. The thing they "invented" was coming up with a loose standard for how to implement your RPC endpoints in a way that the AI was pre-trained to interact with.

The actual implementation may have been very janky but the idea itself is sound: If you want to interact with arbitrary services then providing one single protocol (ideally not JSONRPC but hey) with a standard api discovery method and standard starting method call means your super-intelligent machine god can connect to any MCP service with just a URL and figure everything out from there.

Coming up with solutions isn't so difficult, getting everyone behind one is the hard part. Obviously easier if you're one of the two biggest AI companies in the (Western) world.

It does seem like a return to RPC/REST over HTTP (maybe I am missing some subtleties), which makes sense to me since I never really understood the advantage that MCP bestowed.

They also reinvented CORBA and DCOM, as MCP now supports gRPC as optional protocol.

The reason is that these "folks getting paid several hundred thousand dollars a year" are mostly youngsters without any care to learn about computing history, which is why IT is a fashion industry.

See HTMX as another example, that is basically ASP.NET Ajax or JSF Ajax.

I wonder if part of it was the bias of how the chat apps work with the streaming maybe they use SSE

But I wouldn't discount how uphill it was to probably even argue for something like MCP cause the labs still very scientist-driven and focused on solving everything in token space. The idea that tool use could be super transformative probably wasn't obvious from inside before Claude Code

I had to double take and say "I coulda dun that!!"