That is just plainly not true. I still remember my first time playing through Silent Hill. I was in the last 'dungeon' per say (Don't know what else to call it) and was trying to figure out how to do the puzzle to advance. Well I didn't want to waste all of my ammunition in just killing everything so there would be rooms I left the zombies in because I knew I could avoid them. I'd just gone through one such room and ducked into a 'safe' room that I'd cleared out already and had used a dozen or so times before that. I remember having come to the conclusion that if I don't progress at all the rooms will stay safe. Well that was a mistake to think since I went in and there were two fresh zombies, I freaked out and blasted their heads off with shotgun blasts before I could collect my wits.
While this story I just told does involve a more random sense to it, you have to realize that it was scripted beforehand, and someone with infinite knowledge could know that it was there, but to the average player (which I play games a lot more than the average player) this is going to scare them and accomplish what the programmers wanted, even with it being scripted ahead of time.