It only uses one of the possible outputs but still depends on all of them if all the flags are enabled, which is bad.
I disagree when it comes to oss, alsa, pulseaudio. Global generic USE flags. They are incremental. The package has fallback to wav backend, and I don't want to introduce any USE flag for it for simplish REQUIRED_USE="^^ ( alsa oss pulseaudio wav )" It simply works the way it is now and i'm going to leave it at that.
It should come as no suprise to anyone that setting one of the USE flags will pull in the generic packages the flags come with, alsa for media-libs/alsa-lib, oss for virtual/os-headers, or pulseaudio for media-sound/pulseaudio If there were some extra ordinary dependencies, like media-sound/jack-rack for USE=jack, I would agree that REQUIRED_USE is needed here But not for the generic stuff, it only makes using Portage very annoying
