Low latency audio would fit for doing live or studio audio production, not necessarily watching videos, listening to music or doing video calls (where there is already network delay an order of magnitude larger than the scheduler would impart). "Low" will have context-dependent meaning.
If you're doing low latency audio or flight controls on an aircraft for example, you would absolutely need to abandon the fair scheduler for one that could guarantee the deadlines you need are met. Sacrificing "performance" that is throughput/efficiency/etc of your processor for timing performance.
Think of the difference between doing statistics on a billion lines of data and flight controls on a missile. VERY different needs for scheduling, why not have a selectable algorithm?
