Probably because they want simpler products, without unnecessary fillers, care about more than just "taste" and are not affiliated so don't feel obligated to push their employer's products.
If people want to get the milkshake mouth feel from a low calorie product, then every company will eventually have carageenan, gums, fillers, other additives, etc in their protein powders.
A quick way to gauge the components of this prop blend is to look at the amount of cholesterol. High quality whey concentrates, whey isolates, egg white proteins and micellar casein have low amounts...
In most cases, I don't purchase products with prop blends (the exceptions are when I can deduce the breakdown and/or if its on sale for a very good price).
If you are going to cook with it, it probably won't matter much as other ingredients can help you tweak the taste. Additional cocoa powder, vanilla extract, a few chocolate chips, milk, sweetener of...