I happened a couple of time that when I got killed by a monster in a certain area, when the game restarted, that monster wasn't there no more and the area seems to be cleared now. Could it be because they want you to finish the game so they remove every monster who killed you. Could be pretty lame if you only have to run and get killed to clear an area a process to the next room.
Best I can tell certain monsters are marked to despawn upon killing you. Specific monsters (the first one in the wine cellar?, one of the first Gatherers you ever see) disappear after they kill you, but others (the Gatherer in the Prison blocks) either do not disappear after killing you, or they disappear after killing you several times.
I'm not sure this is sourced anywhere but that's been my personal experience with the game. I haven't actually noticed monsters disappearing after more than one kill either; I'm just guessing, as I've died less than ~3 times to any given instance of a Gatherer I believe. I've definitely seen one gatherer disappear after dying a single time, and another not disappear after dying a couple times to him.
There's definitely some degree of dynamic difficulty intended here, after all the game is about the experience not "beating" it. However if you're afraid you can just die to get past any monster that's not quite true. Several Gatherers will either stick around forever or they'll have to kill you more than once before they disappear.