The reason why MS-DOS text editors were so fast and felt powerful is that they used direct access to video memory to render the text-mode UI.
Unix is still stuck on the notion of the console being an output stream that emulates a Teletype printer at some level. Full-screen text UIs work around this by adding extra layers for screen manipulation in a stream-oriented device.
On MS-DOS, the system APIs were so primitive and limited that everybody (beyond basic CLI tools anyway) just wrote directly against the IBM PC hardware, which conveniently mapped the text-mode screen at a memory location. You could print or move or clear on-screen elements using standard memory operations, and there was no other software layer sitting in between translating the frame buffer, so updates were instant. (No other hardware layers either. The CRT blasted out your characters at most some 15 ms after your update. Today, who knows what’s buffered in the GPU and display itself.)
It’s the difference between a multi-user system where you (as the user) get a narrow stream of I/O with the shared computer vs. a single-user machine where you truly control the device. Sadly the latter model of personal computing is increasingly obsolete.