I'm not sure when the last time you've used a Linux desktop is, but today that is mostly not the case. The third party app ecosystem is relatively strong today on Linux, with multiple implementations of Spotify, Discord and other "must have" apps. Since many of them are simply wrapped in Electron and shipped out to the end user, theming these apps are a cinch. If user empowerment is the topic of conversation, you shouldn't be ushering users to replace their systems with Macs "as soon as {they} have the money."