alt Hacker NewsYes, but it's not like this is some hidden legacy stuff, that you're not supposed to encounter. This is part of the public macOS API: https://developer.apple.com/documentation/appkit/nstext
Every AppKit and Foundation type uses the NS prefix, and will keep doing so for any foreseeable future. New NS types are added to these frameworks each macOS release.
Mission control is not supposed to print the name of the control/window visible to the user though, surely, which is what the article is talking about.