Why AsyncSeq.iterAsyncParallelThrottled is inside this library

[Xyncgas]

The function is accepting a parameter to define the degree of parallelism, I was wondering whether AsyncSeq internally is using dotnet TPL because it already takes processor counts for considerations, meanwhile I wonder how people are finding it necessary to let workloads to run in parallel in the throttled degree of parallelism instead of the highest degree given a processor can handle as much works as that processor can handle