Actually, for a lot of collectors, that's an accurate statement. I don't understand the mindset in the slightest, but it's definitely real. For another example, I don't think Hulk #271 would be nearly as high as it is if Marvel Preview #7 had been a comic rather than a magazine.
I don't get it either. A comic magazine is simply a comic book in larger form. Additionally, comic books were routinely referred to as magazines for decades. Sometimes, right on the cover of the comic. It's two formats of the same thing.