> It's like all the NDAs people sign when they join a company and they pinky promise not to use it at the next job where they land a big fat raise and promotion

Uh no. An NDA would cover proprietary intellectual property, not tools everyone else also uses. Unless you're now working for the previous employer's competitor, it's unlikely that proprietary tech would ever be used. Working for competitors and partners is usually also forbidden for some period of time after leaving.