You're right, I myself don't consider those games to horror games, but there are a lot people with the misconception that they are. The only possible relation they have to "horror" is that they have either zombies or lab-mutants. The gameplay is DEFINITELY not conducive to scaring the player, but due to this slight connection to horror games, and the massive popularity of games like this, people will begin relating "horror" to "running and gunning freaky-looking-things" and not to "scaring the ever-loving pants off of you."
I hope it clarifies what I meant a little bit.
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