Or doesn’t use OS components on any platform. Having a theme that makes them look similar is at best uncanny valley and at worst a huge waste of time for toolkit and developers. Every OS version update tweaks the design I’m an attempt to look new or unique - try to do that across the 5 or more desktop and 3 mobile OS UIs that it supports and you’ll see how every year it would be a full time job just adapting to those trends.