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You’re sounding like one of those people that says “ummm ackshully it’s GNU + Linux, not Linux”
Yes, you can have a desktop without a desktop environment. Well done. Nobody does that in the desktop space. Kate is an OS program.
If you install a distro with KDE, you will have Kate. It’s an OS program.
Case in point, you can install Kate, and Dolphin, on FreeBSD. And on Windows.
Pahahaha, that’s not what defines whether a program is an OS one or not. You can run paint on Linux if you wanted to. Based on your definition, Paint therefore isn’t part of the Windows app suite.
Let’s get back on topic - do you think a normal user will hear “Kate” and think “ah, that must be the text editor!”, do you think they’ll hear “Dolphin” and think “ah, that must be a file manager of some kind!”?
Kate is an OS app. When you install your distro, it’s there.
Well then you’d be wrong about that. Sorry.