Yeah, I'm really getting tired of this "You just changed pages and didn't know it" pattern I'm seeing more and more. I'm not sure why people want to have this single page app at all costs, but if you want the single page app, than a single click of "back" should work.
I think there is value in doing single page apps but mostly for web applications not really for just a website. Still I completely agree that breaking the back button needs to be avoided.
I think a more useful distinction is - mess with back-button history if and only if the user perceives a page transition regardless of if the location bar changed it there was a page load.
