Very good posts by Russ above. And further evidence of why CrossFit can be stupid/dangerous, although he didn't say that in so many words. The rule of thumb I learned for pyometrics depth jumps is short doses: a few weeks a most then wait a few months before doing them again because of the forces and risk of injury involved. Is that still the current thinking?
DOMS seems to be associated with the eccentric component of exercise. If you do stupid crap like many super slow eccentrics, you're going to be sore. I'm a lift fast with controlled eccentric guy; I'm rarely sore. As others have said, you can make gains without being sore.
DOMS can also be induced from a substandard workout if the rest and nutrition are also substandard. So you might get really sore from a workout that's absolutely beneath you because you didn't give your body the other tools it needs to handle a workout; then you fail on all levels.
As for the conventional thinking of plyos... it changes over time and depending on the source. The one thing that is absolutely constant is the recommendation of moderation. Different individuals are going to have tolerances, but in all cases there should be limitations. I like to super-set plyos with my squat sets from time to time. When I do, I usually only do sets of 5. And it's not very frequent, usually when I feel I need to temporarily introduce an extra element.