I'd agree with that. I've tried a few of Fox's pulp stories and barbarian tales (Kothar, wasn't it?) and they read much like a comics script waiting for the artist. Not hopeless or anything, but there was something lacking.
One thing about Fox's super-hero stories was that the villains were never really heinous enough. Robbing was about all they wanted to do. When the JLA's evil counterparts banished the real heroes to space, all they could think of was robbing and stealing. Maybe it was DC policy, maybe the Code was more oppressive in the early 1960s. But Marvel bad guys were genuinely violent and scary, one reason for the rise of the Marvel formula.