I really dislike how people present KDE and Gnome as being "clones" of Windows and MacOS. GNOME specially is so distinct (be it for good and bad reasons) that it deserves to be considered it's own thing. I can't stand MacOS with all it's Macosisms that are ingrained since it's Macintosh days. GNOME being grown for PC usages has none of these issues. Window management is also a breeze and easy to pickup rather than a byzantine mess. The only thing they really share is a nice, sparse look & feel.

KDE does have a lot more similarities to Windows but saying it's a clone might put the wrong idea on peoples mind when they transition from Microsoft's system.

Back in the olden days, Microsoft and Apple did a lot of actual UI research, and for a resource-limited open source project there was no shame in piggybacking on those research results IMHO. But with the 'UX mafia' taking over big companies, nowadays it's reversed, the resource limited open source projects often have better usability.