> what you're saying, if I understand correctly, is that self-hosting this is trivial then

Yes. It comes encouraged.

> so does that mean I could run my own local instance and never get it taken down since traffic would be negligible?

Yes, unless the other end forbids it and really cares about controlling clients. If they do and manage to detect that you are using alternative client they could block based on that. In times where that happens and there are client devs who care, it becomes a cat-and-mouse.