As a long-time Mac user, I'm comfortable with this UI style, but I do recognise that it's weirdly inefficient. It's very strange that this is the UI that won out in the 80s (to the extent that Windows became a massive hit in the 90s, anyway).
A tiling UI would have been much easier to implement! But the original Mac had overlapping windows with pixel-perfect drop shadows. It's a bit nuts when you think about it.