Ask HN: Are NDAs Just Security Theater?

For the past couple of years I've felt NDAs are a form of security theater. They create the illusion of safety, and don't actually make you any safer.

An NDA won't stop anybody from disclosing information, and only regulate the aftermath.

Personally I don't sign NDAs, and was wondering if you generally do sign an NDA? And why, if you ask for somebody to sign an NDA, you do?