[Beltalowda]

There is no "50 years of technical debt". If anything, a significant amount of complexity has been removed compared to the 70s and 80s when everyone and their mother was making wildly incompatible terminals (actual terminals that is, not software terminal emulators).

You don't really need to know anything about shells to write a CLI app, other than basic shell conventions (- for flags, things like that). You don't even need to know all that much about terminals, just some bare basics if you want to do colours or whatnot. All of this can be summarized in a page or two.

If you want to write a ncurses-like library: that's a different story. But then it's no longer a CLI app.