When I visit sites on Dartmoor I never wonder what their purpose is or was , as we will never know the reason, the same with all megalithic sites. We can only speculate. Take Stonehenge as an example, for years everyone has been saying it was there for a midsummer ceremony, now it is thought to be for midwinter.
I first started to visit sites on Dartmoor in the early 1960's, after I came across them while out walking/camping as a teenager. The first one I came across was Hingston Hill / Down Tor stone row I had no idea what ,or how old it was, it was but it fascinated me. What did strike me , and the same with other sites I have visited since, is the setting it was in. This is why I visit sites now, not just for the stones, but for the whole atmosphere of the place that I can just sit and enjoy.

Peace, Lubin