I don't think that one is particularly relevant. The quodlibet author is right to complain there.
Distro users should be reporting bugs in the distro bug tracker, and the distro package maintainer should be the one to surface these to the author, or in that specific case, let it rot because there's no maintainer.
It's completely relevant. The original Debian issue was the same general thing, with the distro packaging QL alongside an incompatible gstreamer leading to bug reports for the dev: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=421167#15
Distro users should be reporting bugs in the distro bug tracker, and the distro package maintainer should be the one to surface these to the author, or in that specific case, let it rot because there's no maintainer.