Denatured proteins = useless ?

Not all of them. Some amino acids we have to get from food.

I'm going to go by the old "bottom line proof" (I'm sure it has a better name but it escapes me atm): Most of the protein we eat (meats, eggs, grains, legumes) is cooked. Yet people are getting bigger and living longer. So either:
- denatured proteins are sufficiently nutritious, despite what whatever source the OP didn't link to says
- normal cooking doesn't denature proteins
- we only need tiny amounts of "raw" proteins, which we get from nuts, seeds, and possibly dairy (does pasteurising denature?)

Regardless, since most of us do seem to be getting all the protein we need as it is, I see no reason to start seeking out more "raw protein" than is already in your diet.

thanks. this is much more helpful. so i guess it is okay to mix protein powder with hot water, fully cook eggs and such ?