Is it just that directing credits - especially major ones - are considered more significant? Because all the good films he directed, he also wrote or co-wrote, plus Ghostbusters, Ghostbusters II, Animal House, Meatballs, Stripes, and Caddyshack II. And was head writer on SCTV for several years.

The contribution bible doesn't say a whole lot about the "Known For" criteria, so I'm curious.