As every theory has on ruins, one theory that stands out the most which is a very common one since I've also read this kind of thing in novels is that, what happens outside can't be known on the inside and vice versa.
This proves the reason that ruins are in a different dimension, which they wanted to call since it's connected and disconnected in the real world at the same time.
Now, why was I thinking about this? Well, because I don't know what was happening outside.
There's no need to mention the telegraph since it's not working inside the ruins, which explains why all the explorations and raids on the ruins are in the dark due to not being able to communicate one's self situation on the inside.
And not knowing anything outside is one of the many things I fear the most. And the oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown.
