It’s a pattern that I’ve seen called dialog tunneling, and I think the most prominent example of it is Windows 9x up through 7. Web apps are pretty bad about it too though, more often than not because navigation can’t be made sensible when there’s a new feature that needs to be shoved in front of users every few weeks/months, so stuff ends up getting buried in dialogs N deep to make room.

Definitely registers as poor UX in my book.