The .NET libraries make it easy to use the default thread pool (a single pool). If other libraries are similar, then I wouldn't consider this a complete straw man.
Yes, but the .NET thread pool is auto-tuning, although very badly, with at least a second latency to increased workload. For bursty requests that could be done within a few hundred milliseconds it is a bad fit. But you can't DOS your batch processing server so easily.
