Watching Clint's video on proper technique, IMO, the main reason to have a shockwave is for portability / concealability. If I'm pushing the shotgun out in front of me as he demonstrates, that just seems awkward compared to just having a full stock I can push into my shoulder. Or just getting a folding stock tactical shotgun for portability.
I mean, yeah, you use a similar technique with AR pistols if their brace is folded, but there's a lot less recoil to contend with for follow up shots.
JMHO.