As someone else with a small laptop display, I run everything in fullscreen mode, and toggle out whenever I need to use the controls. If you’re hiding the controls anyway, why not just use fullscreen mode? Then, when you want the controls, you don’t need to have them hidden in a bunch of layers, they can just all be there.

Hey, whatever if we just made all the browser controls a modal or fullscreen context of it’s own?

You can't always use full screen, often you need to have multiple windows open next to each other, and that's where minimizing chrome is especially important, because your windows are smaller now but the size of the chrome remains the same.

Multiple address and tab bars next to each other doesn't work well on a small laptop. Separating them works much better.