You are mixing up capabilities with inconvenience.
If OS X also had tailor made kernel just for lower real time latency it could do even better.
But out of box, it's already better.
That said, the point is moot. 99% of pro audio/MIDI apps/VSTs don't run on Linux, so only experimental nerdy musicians and FOSS zealots would use it for real studio work. You do get the occasional profile on music tech websites e.g. "Techno musician X uses Linux", and somebody always jumps in a forum to say they use some Linux DAW (and usually add a list of ugly hacks, workarounds, and things that don't work), but it's clearly a total outlier situation...
Nobody said Linux can't for some law of nature run music software.
But it's empirically true that it both lacks 99% of music software people want to run, and that it's not used by 99% of musicians...
Regular people aren't compiling kernels.