A problem here is the tendency to want to make things black and white when the real world is many shades of grey.
A few thoughts ..
When we refer to a stalling angle of around 16deg, that is appropriate for an older, traditional aerofoil profile and is the typical dumbed down story for new pilots.
As with any form of training or information transfer, the detail level needs to be appropriate to the needs and comprehension of the trainee. For the new chum, the story needs to be simplistic until the basic ideas are comprehended and then the student can be introduced to more complex and detailed stories about what might be happening.
Doesn't matter whether we are talking about Scouts or similar learning the absolute basics for a badge of some sort through to trainee pilots then progressing to airline folk or, for that matter, first aiders progressing over a period of time to become brain surgeons .. same principle applies.
Keep in mind that any of the nice pictures you see will be generated from (typically tunnel) data for quasi-steady flow states. Once you get out into the real world it starts to get a little muddied.
It is a term that trevor thom uses in his books
Critical angle is fine to think about .. whatever it might be for a particular aerofoil section .. somewhat below that and things are comfortable .. progressing to more interesting things as you increase to higher angles. Please don't suggest that 16 deg is the number for all wings .. that's nonsense. The basic textbook Cl by alpha characteristic is sort of typical but varies a LOT according to the profile and, also, pitch rate (especially for helicopters).
I haven't spoken to Trev for many years now .. he did a lot of good work in the original development of his books (with a bit of help from a few of us along the way). Flew with him a few times in years long gone by ... thoroughly nice chap. I would imagine that the present business, run by Dave Robson, still is a purveyor of fine books albeit, I imagine, with a bit more of an emphasis on technical rigour. Flew with Dave only the once and that, many, many years ago.