For an early stage company (first two or three funding rounds), it's probably a good way to get mocked, on either side. As a founder asking a VC to sign an NDA

For an early stage company (first two or three funding rounds), it's probably a good way to get mocked, on either side. As a founder asking a VC to sign an NDA you look like an inexperienced idiot, and as a VC you look like a pompous idiot. For later rounds with high investor demand to be the last private money before IPO, I could see the justification for founders asking to sign an NDA. And investors don't really have any leverage in that situation. They don't have to sign the NDA but the founders don't need their money, either.