Beside looking cool they'll serve no purpose while plinking at the range.
Lol tell that to this chap!
That is the Dlask slant brake that was infamous for overcompensating. You can see it forcing the buttstock up into his face.... no full auto required for it to do that. And id say thats pretty sound proof that while plinking they can serve a purpose... and even surpass it in an unpleasant way if designed wrong.