Yeah, I don’t get how you distinguish between a correct visual proof and a visual proof that looks right but doesn’t actually prove what it’s trying to prove. You could probably make a pretty convincing-looking visual proof that the limit of the sum of the harmonic series is below some finite number, that 0.9 repeating is less than 1, that there are more rationals than integers, that there are the same number of reals and rationals, and that sort of thing.

On the linked page, a lot of the proofs are essentially proofs by induction that stop at some (pretty small) n. Maybe there’s a way to make it rigorous by visually showing the induction step that proves n+1 given n, but if there is, it’s not shown.

This can be great for building intuition for a statement known to be true by other means, but I wouldn’t consider them to be proofs.