I imagine that "no studying" should really be read as "no loitering." Or perhaps "this is not the place to come and read all day, please, there are other people

I imagine that "no studying" should really be read as "no loitering." Or perhaps "this is not the place to come and read all day, please, there are other people who need to use this space." It was probably a problem. I've seen such signs at cheap chain restaurants in Japan. (I'm not attempting to generalize here, just relating an experience) The clear message was that high schoolers would come and buy the $3 all-you-can-drink soda package and sit and study and chat all day. Hence, no studying. Seems reasonable enough. Many places don't have that rule though, and there you can see many people studying all day.