Sad to say I've encountered variations on that mindset in my life. When I was very young, some fellow Star Trek fans actually turned on me because I dared to like Space 1999. For them, to watch or like any other franchise was somehow tearing down Trek. Had there been internet back then, there probably would have been a lot of mindless bashing like we have now.

This craziness even manifested itself again into people picketing in front of theaters showing Star Wars at one point. IIRC, no less than Gene Roddenberry told these fans to knock it off.