Dumb question: Why do we need many independent Node.js runtimes?

We need them so you can pick and choose the one that works best for your current project.

But that points to an important aspect of the platforms-game: The interface between the runtime and everything else should be standardized, to support true pick-and-choose.

I believe it indicates a healthy market and pushes competition and better outcomes for customers. In this case, Deno pushed Web primitives for Node.js and Bun pushed forward on speed (and helped Node.js work on their numbers better).

This have a similar analogy with browsers. Back then when Internet Explorer was the only supported browser, the websites were not evolving as fast. When Firefox pushed it forward and then Chrome, customers won (better and faster sites).

Well it keeps all the node developers away from my shit so I'm happy :)