I'd still prioritize the basic use case of comfortably typing words, which to my admittedly sensitive mind is not supported that well anymore by some common pieces of software. Between the apparent round-trip per keypress in Outlook Web, the noticeable general display delay of Windows 10, and the frequent wait for characters to appear in a reasonably small Powerpoint presentation, I feel like I might be holding it wrong.

Quite often it would not be usecases, but externalities. That is, trading the quality and efficiency of your product for some benefits in selling or developing.

Software, for better or worse, is a social enterprise, so you can get away with dumping a lot on your users before they pack up and look for alternatives.

Ok, and a lot of non-user-facing cruft too.