Let's look at it this way. When you're sore, your muscles are at probably 70%. If you keep attempting at being sore, your muscles efficiency will decrease to 60-50...maybe even 40% only. Now this brings on three probs.

1. You cannot have maximal hypertrophy (if you're looking at it the bodybuilders way) and that will suck as a certain percentage of your muscles have to overcompensate and then you have this weird physique that looks...weird. Overcompensation then brings us to the next problem;

2. You get injuries, because your constantly sore muscles cannot perform fully and and under perform causing stabilizer and surrounding muscles to work doubly hard. Adhesion will cause tissue build-up that doesn't perform. Yay for useless muscle (that's hiding a constant injury)

3. You feel like shit.

At least based on studies thats what I've found out. Personal observation, yes to 2 and 3. As for the 1st one, I'm unsure because hypertrophy isn't exactly my main goal here.