Its definitely more a strategy that works in very specific instances, but players usually seem to expect and thus prepare for fighting a small handful of good units and not a huge swarm of crap ones so you can take advantage of it to whack their best stuff in the start.

Literally anyone who brings cluster bomb air can counter it pretty well, but if you have a teammate who can counter their air then hilarity ensues (usually).

in-game speaking this is really hard to pull off, specially since they dont have good accuracy