I might be wrong but I get the impression that all that is being legislated is the quality of the supplements - not their efficiency. Theoretically you could have a dietary supplement made out of cotton candy, and as long as it's manufactured, distributed and properly tested for stated ingredients you could still sell it as a dietary supplement.
In other words, they don't care if it doesn't DO anything of value, as long as there are no rat-hairs in it.
This is doing nothing but increasing the cost of legitimate supplement manufacturers, which might be the entire plan of the FDA and their puppet-master Big Pharma after all ...