For me it's a toy at the moment, but from time to time I want a Linux GUI to test something.
My assumption this is more performant than sticking something in VirtualBox (purely assumption).
Could be handy if you have an industry specific Linux only GUI app and give out remote access to it.
I'm currently a bit of a fan of the LinuxServer.io stuff. I'm clueless about docker and they have packaged many cool open source applications. So far I have used one, and it just works.
And the people on discord were quite helpful when asking docker questions.