Desktops could be improved quite a bit by tweaking default nice and ionice priorities for apps, instead of relying on one scheduling algorithm to be able to just "figure it out" on desktops, servers, phones, etc. A memory eviction priority, if niceness isn't treated as memory priority, could also help, but the existing tools can already go a long way and they just aren't being used.

I was able to get glitch-free audio by tweaking software and soft-irq realtime and non-realtime priorities, when the default Ububtu (with low-latency kernel) was nearly unusable for audio.