Anubis doesn't require docker. It's also incredibly easy to setup. It took me 20 minutes. Running a native binary, no docker. It doesn't need nginx. I use Apache and it was 5-6 lines of code to setup the config in Apache to proxy to then talk to my website (the same Apache config/server)

In the time it took to write that blog post they'd have been able to set it up 5 times over. I expect there's some other reason they don't want to use it (probably that god awful mascot)