"In 1993, Netpbm was developed to replace Pbmplus. Netpbm was nothing more than a new release of Pbmplus, and named for the fact that people all over the world would maintain the package by submitting fixes and enhancements over the Net. This was a time when such worldwide collaboration was still novel."
Stuff usually gets "net" slapped on the front after some attempt has been made to specify or regularize it, that way the documented/maintained version doesn't share the name with any classic implementation, which helps to avoid all kinds of ambiguity.
Not sure where this idiom came from, but seen it used a bunch of times
Nethack? NetBSD? Netatalk?
netatalk is likely just a dir name, like netinet or netns.