I was thinking more specifically of things like having to configure HiDPI settings differently for Qt and GTK, for example. There are also some copybuffer inconsistencies at times. It's not a big deal for anyone who is motivated to deal with it, but probably irritating enough to make some people give up early on even if they would otherwise like having a system that's configured properly.

Oh yes, I agree, DPI settings should be global accross the system as much as possible and copy buffer should definetly work consistently. Generally it's the application's responsibility to implement the tie in to these platform systems - on the interface level that should preferably not be tied inseparably to any UI code).

To me however, this is on a different architectural level than how the UI itself is inplemented (which, technically, is just motion graphics with hotspots, but psychologically is the most important part for most users).

Yes. I have never got that insistence on UI nativity. Is there any OS where it's actually practical to only use programs that conform exactly to the vendor's UI style? All the major desktop OSes depend on tons of "non-native" programs to actually do work. Android usually requires some, and I'm not sure about iOS as I've never seriously used it, but I would guess the case is similar there.

It seems like "must be UI native" is a way for Mac fanboys to try to enforce their preferred design paradigm on otherwise-uninterested people.

To give credit - Apples human interface guidelines for the original Macintosh were wonderfull in giving guidance where the UI as a concept was bound to be foreign to most. Also, the first commodity GUIs were on resource strained hardware so they could not do everything effectively.

I think we are now at a point where the glowing animated screen is far more familiar to most people and the raw power available on most devices is such the only rational constraint for UI design is that use experience must be understandable to most and that the underlying system must play nicely with rest of the device.

If I have a choice, I'm always choosing native application for macOS. It's eating less memory (because all shared libraries are already loaded), it provides similar experience as other apps (menu bar, context menu), it's usually works much faster (because Objective C is quite fast compared to some interpreted languages). Sometimes I don't have a choice (like Intellij Idea), so I have to live with Java or Chromium application, but I don't like that experience.

I agree completely. Most big desktop applications make no attempt to conform to platform look and I have never heard people complain of that.