That is a very interesting question Ashis. Thanks for bringing it up.

I can tell you from my first hand experience of having supervised a couple of MSWs under me in the very recent past, they are invaluable. The advantage they have over a regular HR professional, is that they are more prone to the humane side of the job than a regular HR professional. For example, if there is an event that our firm was organizing where the parents of our campus offered candidates were to be brought to the office, the regular HR guy is happy with making the arrangements for who would speak, how long, coordination of the event, etc. This particular MSW was the one who brought up minute, humane needs like arranging transport for them, keeping umbrellas at each of our buildings so that, IF it rains, the parents should not get drenched, etc.
Having said that, I am by no means demeaning the value that a regular HR professional brings to the table, but I would like to emphasize that an MSW is as good as any HR professional and they deserve to be in the domain.
Open to discuss.