Well, I kind of agree with him. I never particularly liked the superhero comics, and more importantly, never understood how it got so big in first place. It seems a weird anomaly to me.
I'm not saying they shouldn't exist. But it's something incredibly specific right, if you think about it. It's not a genre like "adventure" or "drama" or "romance" are genres, but (in very general terms, of course there are exceptions) a very specific sub-genre: about good heroes that dress on costumes and have fake names that evil fight villains with some kind of super powers .
Something that specific should be a 10% of less of a entire medium like American Comics, but somehow it expanded to be the 90% and the rest of genres is the 10%.
No genre dominates like that other mediums like fiction books or films, and much less something that sounds so niche, but in western comic they get away with it.
A good time ago, I read an article about Stan Lee creating 3 novel comics, totally new. And the three descriptions were about superheroes. It's like in his mind the possibility of doing a story that didn't involve people with superheroes didn't even occur.
edit: BTW, I doubt the Alan Moore's audience in the last 15 years is the same public he is looking down here.