But take a look at the following chart comparing the genres Seitz cites:

This chart, cribbed together from a few different sources, gives an estimate of the growth of zombie, western, and superhero movies from 1930 to 2013. It attempts to stick to American movies, although US cuts of foreign films have surely snuck in. It includes older double-heading serials and some direct-to-DVD fare. It is almost definitely incomplete. Even so, it’s clear that throwing superhero movies in with the other genres is, numerically, comparing flying apples to tobacco-juice-spitting oranges.

For example, superhero movies haven’t had nearly as much time to compete. The first zombie movie came out in 1932, which is why the chart starts there. But westerns had a lead of hundreds of short films and serials. There were “westerns” as early as the late eighteen-hundreds. Meanwhile, the first Batman movie didn't come out until 1966.

The chart also shows how long it takes to get to the “poets of genre.” By the time we get to High Noon, Shane, and The Searchers (all AFI Top 10 Westerns), there had already been more than 1500 movie westerns made. After accounting for the fact that many of the early westerns were only an hour long, that’s still more than 750 hours of lassos and revolvers.

Even when considering zombies as separate from the larger horror tradition (whose numbers have long surpassed westerns and was going strong in the ’50s), there had already been about 36 predecessors to George A. Romero’s 1968 Night of the Living Dead. And many of the most lauded non-Romero zombie films, including most that Seitz lists, have come out in the last 10 years. That’s a 30-year gap filled mostly with titles like Curse of the Living Dead, Garden of the Dead, Return of the Blind Dead, and Deathy Deathy Death Death 3: More Death. Critics say that quality movies like The Incredibles and Hellboy are outliers, but your odds of finding a good superhero movie on average remain far greater than finding a good horror movie. So while Seitz is right that most superhero movies aren’t Hellboy, it’s actually truer to say that most westerns aren’t Silverado and most zombie movies aren’t 28 Days Later.

Now, I don’t mean to suggest that the quality of a genre is related solely to its lifespan. Genres don’t evolve in isolation. Last summer Zack Snyder with Man of Steel was not just having a frame-by-frame conversation with 1951’s Superman and the Mole Men. But even so, there have been many wonderful films in the past 50 years—shouldn’t the vast amount of good examples available to contemporary filmmakers have made everything much better by now? And yet garbage persists.

It seems that to get genre fare that approaches art, expect to wade through a lot of trashy entertainment. The quality and range of the western and zombie canons probably have little to do with the inherent crudity of genre, and a lot to do with having been around long enough to offer opportunities for different generations and artists to add their own touch.