It was ridiculous the amount of B.S. we were taught and expected to feed the customers to make a sale. I actually used to work for the GNC at Eaton Center (second largest in sales volume in the world, top sales store is in Hawaii). The guys who I used to work with had to sell this BS as our jobs depended on it. A lot of the guys who didn't spew out the BS we were told were either fired or ended up getting offered jobs working for product vendors.
Honestly, the supplement industry is the biggest reason why these myths continue to live on and just won't die.
You'll never hear guys like those total con-artists who work for MuscleTech saying that you should eat whole foods whenever possible and that meal timing is not important. Of course not, they will continue to tell you that you need to eat 6 times a day and that between your 3 square meals of chicken breast, brown rice and steam veges, that you need to supplement with MRPs & Protein shakes. And lets not forget the expensive cocktail of supplements would have customers subscribing to. Those silly little rules like only being able to absorb x amount of protein in a single meal. Its all a joke to me now.
I think, what also helps prevent the myths from dying off is that to a degree they still work. A lot of guys follow the 6 meals a day plan and chow on a lot of expensive supplements and achieve good success. So, it may be hard for the less informed to really see why there is a problem with this formula.
For me the problem with this formula is that I do not think it is the most efficient way to achieve the best possible results. It is a way to do it but I don't think its the best way.
I use to train 5-6 a week, eat 6 times a day, PWO shakes, I use to watch my fat consumption (esp saturated) and did what I thought was the right thing. I now train 3 times a week, eat 3 times a day consisting of eat meat/fish/eggs, tubers, veges and fruit. I also eat lots of fat. I also track my results and can see that I am much better off since making the switch. Body composition is better, Im stronger, less wear and tear on my body, my eating patterns are far easier to deal with. That is just my experience though.