Interestingly enough, Masello's attitude toward adjectives is more in line with the standard attitude toward adverbs.
Whereas in his previous rule Masello chooses not to condemn writers who go overboard with their adverbs, he does take a shot at writers who go overboard with their adjectives. In particular, he criticizes prose in which many adjectives are used to modify one noun. In fact, I can't resist quoting one of his comments here:
...And adjectives, like gang members, seldom ventured out alone. They went out in twos and threes, and God help us, fours, and piled up on any person, place or thing that got in their way. "Look! It's a noun -- let's get it!"
I like that image.
But I think I see where his perspective comes from. Even though we are constantly warned about the dangers of adverbs, the fact is that standard grammar usually only allows for one adverb at a time. If I wanted to pile on the adverbs, I would soon come to realize that the repetition of the "-ly" syllable was draining my sentence of its power.
Observe what I mean:
Overuse of adverbs: He stood proudly, defiantly, and forcefully.
Overuse of adjectives: The proud, defiant, forceful man stood.
In both cases, I'm using a lot of commas, but to my ears the first sentence feels more intuitively wrong than the second.
But the second sentence isn't such a hot one, either, which I think is Masello's point. We've become so careful of watching out for overuse of adverbs that we forget to be sparing of our adjectives as well.