Because, people keep confusing proofs with theorems. The proof can be correct, while the theorem is the wrong one. And if you got the wrong theorem, you might not be interested in its proof (sometimes you are, anyway).
This.
Now, write a theorem describing a non-trivial piece of software. Is your theorem longer or shorter than the source code? Easier or harder to read?
This.
Now, write a theorem describing a non-trivial piece of software. Is your theorem longer or shorter than the source code? Easier or harder to read?