I guess I also don't understand the "closing the lid to leave" behavior as well. My laptop is integrated into a desktop setup with external monitors and it only gets closed when I actually take it out of the house. Otherwise screen locking and letting the monitors go sleep is fine with me
Say no more. In my experience most of the "linux is fine for laptop usage" folks tend to be "laptop is actually a desktop that I rarely if ever take anywhere" folks also.