Well, he wasn't exactly in a position to be subtle. He was a proponent of Sci-Fi novels, back when they were first getting big, and people where claiming they would rot your brain and make children violent. (Sound familiar?)
Somebody told him that 90% of sci-fi was crud and drivel.
He said, "Sure 90% of sci-fi is crud, that's because 90% of everything is crud."
The point being, you shouldn't judge a genre from the worst available examples, or even the majority or it's contents.
Literature isn't respected because of the cheap pulp novels they sell at the drugstore. People respect literature because it produced the classics.
90% of all modern poetry is garbage, but enough of it is good that people still write poems, and great poems are still written, etc.
Maybe more than that with poems and comics, because those mediums are favored by beginners and adolescents, who tent to produce crud at an elevated rate.
