The default thread pool will use all available cores on the machine. With multiple developers arbitrarily using parallel streams in business logic because it "sounds faster" there is more risk of disrupting concurrent requests.
> The default thread pool will use all available cores on the machine
This is actually a bit of a headache on many-core machines for another reason.
e.g. my production machine has 128 cores, and carelessly parallelizing a memory hungry task (not realizing it will run across 128 threads), risks allocating sevral hundred gigabytes of RAM, and may not even be faster given all the NUMA overhead when thrashing on all cores.
Have to be careful to always down-tune the common pool size to 32 or something.