Because, Slam, folk still keep using the term 'stall speed' as if that's a 'carved in stone' speed below which the wing will stall and above which it won't. That would be merely semantics if it weren't for the fact that people die in low level stall spin accidents while religiously observing 'the stall speed' without realising there isn't one. Or that there is an infinite number of them - the same thing really.
The term is meaningless, a hang-over from basic training where studes need something simple to observe which, in the limited envelope of initial flight training, will keep them safe.
It's a term that should be left behind for the correct one, stall angle, in post PPL flying. Continued use of such an inaccurate term indicates that pilots might not really understand how a wing works, and why it sometimes doesn't. That can be fatal as one extends the envelope beyond straight and level and rate one.