All this is true, but it's also true that there's something of a historical rivalry between Marvel and DC, or between their fans. Although, as I said, that hasn't stopped countless people from working for both.
(I was surprised in reading Lou Scheimer: Creating the Filmation Generation
the other day that Scheimer worked briefly at Hanna-Barbera before founding Filmation. Having grown up in a day when Filmation and H-B were the DC and Marvel of Saturday morning cartoons (or maybe vice-versa) -- the Big Two battling for dominance -- I found that rather shocking and hard to conceive.)