This property is definitely one of the things I love about PHP -- when the request is done, everything is thrown away. This encourages you to do the minimum amount of work to get your HTML (or whatever) out the door. I'd like to say it forces you, but it doesn't really -- I've seen plenty of 'lightweight frameworks' that mess around for 50 ms creating cathedrals of objects that just get thrown away on a hello world page; if you do the minimum amount of work, you can get pages out the door pretty quick. Layering and abstraction can solve a lot of things, but it can't solve wrong abstractions.
What I find ironic is that creating the illusion of state in php is an absolute pain without a framework, which again applies to most language/server combos I've tried.