If there are multiple options, how would QA ensure that these options aren't buggy? I mean the QA in either something like GNOME, a small project, or a distribu

If there are multiple options, how would QA ensure that these options aren't buggy? I mean the QA in either something like GNOME, a small project, or a distribution. Just combine the different amount of sound systems (seems to be popular in these comments). Now combine those different systems with different versions of the kernel and e.g. ALSA. Then sometimes things just don't work because of a combination of the sound system and the bug in the kernel (only exposed in one sound system). Way easier to just standardize on one. E.g. rely on PulseAudio. Then you can still make a standard to have PulseAudio and JACK work together (something that it seems most people here overlooked), but for your project the QA is easier.