The tutorial is very well made and examples are totally relevant, I am sure that many will benefit from it, but the technique in itself is fairly obvious isn't it?
I would think that most people already combine curves with masks, and the basic idea of a curve is that you can determine what tonal range is going to be affected, isn't it? What PS brings to the picture compared to, say most of the RAW conversion softwares, is local modifications thanks to masking, as opposed to global modifications.
To my eyes, PS has little value if this was not understood. Putting it the other way around, what were you guys doing with PS if you weren't doing some variant of this already?
I'd say that the only aspect average PS users like me don't always think of doing is to use Luminosity mode instead of Normal mode to avoid hues modifications.
Cheers,
Bernard