I have never moved in with a girl, most people I talked to say the same things as you however. Even though I understand the logic why you shouldn't move in with a girl, I can't also see how you can make things work in the long run.
For example, how can you demand a girl to drop her single habits, such as girls night outs if you don't want to move in with her? She simply has lots of free time in the evenings, and she is gonna fill them somehow. She can't drop all her hobbies etc for you without receiving anything from you in return.
On the other hand, why would you move in with a girl who, for example, goes to girls night outs? You might be able to draw a line so that she stops doing such things, and she will comply for a while. But again there is no guarantee that she will keep complying when she gets what she wants (moving in with you).
It appears to me that this is the status of the current dating market. There is no way to win the LTR game. It's a lose-lose proposition unfortunately.