Modal editors can be (in principle) made non-modal by changing keybinds to combos that change modes behind your back, so you'll keep insert mode as your primary one. So strictly speaking, non-modal editors are the ones that force you into only one style
But not sure real editors are as capable since some can have adverse actions on mode changes (e.g. resetting your selection or changing undo stack etc)
Yup, I know what you're talking about. Evil-mode in Emacs actually adds so many nice features and simplifies so many things outside of text editing, yet I've never seen anyone who dislikes modal editing actually install evil-mode and keep it disabled by default. Them Emacs veteran "nevervimmers" are missing out.
But not sure real editors are as capable since some can have adverse actions on mode changes (e.g. resetting your selection or changing undo stack etc)