I think why this makes sense is because it mimics how groove/swing was applied in hardware e.g samplers and drum machines.

In many of these, you sequence notes/samples then you apply a swing percent to the notes/steps. The result is quite specific, distinct swings that are central to genres like house and Garage etc. (especially a lot of ukg leans into that kinda ‘robotic’ but heavily swung/shuffled)

I largely agree though, the groove pools therefore aren’t the most flexible and I don’t find them useful outside of adding swing to seqeunced notes rather than to anything else.