There are oter possibilites, maybe the couldn't keep up the rent to keep the buildng so they left it, there could possibly be some sort of health hazard in the building, or maybe there was some sort of lawsuit and they had to close it down. There's also the possibility of tearingit down might be illegal. That actually looks like mold on the walls in the photo and that's definitely a health hazard.
Hehe, I know or sure near Philadelphia, Pensylvania... there's what remains of a mental hospital called Penhurst, it was completed in the early 1900s and was open until the 80s. but they got chewed out in the late 60s because of the terrible things that they were doing to their patients. It took them a long time to ge photo evidence, and when they did, two lawsuits were filed against them and they lost a lot of money. There's a documentary on it on youtube, kinda blurry, but it's still watchable. The buildings of the place are all completely "abadoned" now. There's some speculation about things going on there and they aren't gang things.