That is correct. Superhero comics didn't dominate newsstands back in the day.
Those sales numbers are essentially accurate. There's no reason to expect them to reflect the titles that are most highly prized by collectors today. Quite simply today's collector market largely grew out of the niche of MMMS members Stan Lee generated. Sure comic collectors existed before then, but the Marvel Universe that Stan Lee created resulted in a quantum leap in the number of collectors. Julius Schwartz and Mort Weisinger also had a hand in fostering this quantum leap but Stan was nonetheless the Man when it came to encouraging comic buyers to hoard comics.
Today's comic collecting community can trace its origins to the Real Frantic Ones who bought Marvel comics from the Silver Age to the early Bronze Age. The few collectors who were drawn into comic fandom by "Duck" and other Dell comics in the 1950's are a small and ever decreasing niche. The genres from the 1940's and 1950's that have seen the most growth in demand in the last fifty years are precisely those titles that most appeal to today's rapidly aging Marvel Zombie contingent, e.g. crime and horror. Though I find this sad, it's undeniable.