"You can please some of the people all of the time, you can please all of the people some of the time, but you can’t please all of the people all of the time"
I think a lack of focus in development, with the purpose of trying to please everyone, is a huge novice mistake when it comes to development.
Not these days anymore. Platform specific releases of desktop applications like these is a major novice mistake which inherits outdated mindset from the previous era. Unless we are talking about low level code.
Says who? Last time I checked, in all major platforms (Windows, Mac, Linux) there are platform specific releases that are doing great (commercial and open source).
(note: I consider KDE/Gnome programs as "Linux/*BSD-specific releases", which they pretty much are in practice).
If you have resources for such releases. We are talking about another choice here (i.e. either one platform only with native UI, or many platforms with cross platform one).
Qt has gotten much better over the past few years, but Qt apps on OS X still stick out like a sore thumb to anyone who is familiar with what Cocoa provides for free that Qt has to emulate.
Far more sane to have POSIX core code, then develop the GUI for each platform in the preferred mode.
And when it comes to graphics and drawing, divergences become even more extreme. POSIX is not relevant when it comes to pushing pixels.