Because when you want to record your instrument along with whatever else is in your project, timing is critical and everything needs to line up.
You cannot be performing to audio that you are hearing with any delay, especially if the monitoring of the live audio is also being routed through software.
At a certain point of latency it introduced delays and badly affects how you perform. In some circumstances it makes performance actually impossible.
There are ways around this, namely if the software knows exactly what the input and output latency is then the playback and recording can be compensated. For live monitoring though you really need that done in the audio hardware itself in hard real time.
You cannot be performing to audio that you are hearing with any delay, especially if the monitoring of the live audio is also being routed through software.
At a certain point of latency it introduced delays and badly affects how you perform. In some circumstances it makes performance actually impossible.
There are ways around this, namely if the software knows exactly what the input and output latency is then the playback and recording can be compensated. For live monitoring though you really need that done in the audio hardware itself in hard real time.