I mean, one could say no one ever writes a book, they just discover it, since that sequence of characters (like all other sequences) was already implicit in reality.

I think this points up the problem with what you're claiming. There is sufficient creativity to get to the exact sequence of characters (or exact configuration of elements for the invention) to distinguish invention (a kind of creation) from mere discovery.

In mathematics, though, we say a mathematician discovers a proof, even if the proof is very creative. So maybe it's not as clear as all that.

Maybe the problem is the nature of constraints around the innovation? If it's sufficiently constrained there's little room for creativity, and the word discovery is more appropriate, even if it was hard to find.