I don’t really agree. The global menubar is a central pillar of the Mac desktop, so it being missing (or only present sometimes) is a big problem, and there’s lots of smaller things like differing conventions and design approaches. By my estimation, the furthest KDE can be made Mac-like is 55-60%. Anything further is going to take forking and wading through code.
The funny thing is, KDE 3.5.x had the global menu bar as a feature. It didn't get ported to >4.x since there was not much interest.
I guess it still can be done.
How mouse/keys/scrolling behaves, what pointing devices do in what cases are easy cases for KDE. Notification system is also pretty powerful.
The reality is, everything is cross-pollinating from each other. Even if making pixel-perfect copies is not possible, both are pretty interchangeable.
I use both Macs and KDE for more than 15 years now, and can switch from one to other instantly. Both are in front of me during a normal workday, and I just switch without thinking.