>> Why soy protein. What else is so cheap.
Your post reminds me of someone I dealt with a few years ago. She was a bodybuilder and fitness model. For the most part, she had great (mostly paleo) advice for everyone at work... that is, until it came to soy protein.
She was always advising everyone to eat minimally prepared, un-processed foods. But then, she would always ruin it by extolling the "virtues" of soy protein. I argued with her that soy protein is likely the MOST PROCESSED food you could possibly find, but it more or less fell on deaf ears.
The soy lobby is pretty powerful.