The Backrooms represent many things, including man's fear of being lost, isolated, and, in some cases, found.
The levels are massive; massive enough to provoke a fear of being lost.
The clusters are even larger, and even though you're not alone, you are usually by yourself, invoking a fear of isolation.
Then, the entities. So many entities that can invoke so many fears, including the fear of being found.
Now how can you be scared of being found and lost at the same time. Easy answer: Who knows? Certainly not me. But, it is a thing, so might as well let it be.