You are mixing theory with practice. In theory felines can be both cats and tigers. In practice the felines walking around your neighborhood are all cats.
No of course not, that's an absolutely ridiculous thing to say. ∀A -> B does not mean ∀B -> A, it only means ∃B -> A.
tsc, the executable, not only supports TypeScript, the language, but also knows how to read JSDoc when you're not giving it TypeScript. It supports JSDoc for code that isn't TypeScript. I'd repeat that a few more times but hopefully twice is enough to make the point obvious.
Sure. In theory people could be doing that. But for the third time: what is happening in practice?
What people _could_ be doing vs what they _are_ doing was explicitly my point, so please stop pretending it wasn't, less we have to repeat this merry go round.
If the question is about whether JSDoc is TypeScript, and you want to turn it into a different question, maybe your question belongs in a different thread.
JDoc, the spec and docs-in-practice, is not TypeScript, the language and tooling ecosystem in practice, and does not have type annotation parity with TypeScript (so it's not even "the choice is arbitrary in practice because they do the same thing").
JSDoc is simply a supported spec by the TypeScript tooling. Saying "JSDoc is TypeScript" when you're a programmer, especially one that uses one or the other, is idiotic: your job relies on precision in both code and terminology.
