[GaryBluto]

Windows Aero did work, or at least the Windows 7 incarnation of it.

[knollimar]

Wasn't it a bastardized watered down version that cached the elements behind it and still gave a performance hit?

They seem to be running into the same issues and didn't take the learned lessons with them

[flohofwoe]

It was still ugly, but it did kinda work because it only affected the window chrome, and it could be set to opaque with an easy-to-find setting.

On macOS the checkbox for "Reduce transparency" is hidden away in the Accessibility settings panel which is the last place I'd look for configuring the desktop theme.