@frumble And it is true, icon themes have been a major sticking point for app developers for a very long time. You never know what icons you're going to find, and how they are going to look on other distros.
I remember having this issue all the way back in 2013 when moving a simple app across distros meant the whole UI was broken due to missing/renamed icons. This makes it impossible for developers to offer a cohesive experience, so devs just give up and vendors their own icons.
bragefuglseth