I'd have to disagree. Rockwool/703 is not a panacea.
The decay time of the bass gets shorter ... this is good
The decay time of the highs becomes even shorter than the bass ... this is bad
The nulls in the room become shallower ... this is good
The "Q" of the nulls change... they become wider, and easier to perceive... this is bad
The comb filtering from early reflections goes away... this is good
The remaining reflective spots become even more noticeable... this is bad
Overall the effect is positive, but not overwhelmingly so. And you could spend $thousands, and lose dozens of useful cubic feet before the room modes are reasonably tamed.
Most "bass trap" products have reduced absorption in the high frequencies, so they must recognize some of the fallacy of "absorbing everything".
One thing is sure: Rockwool/703 is easy to come by. But "if all you have is a hammer, everything looks like a nail"
-Ben Loftis
Studio Outfitters