I used to think knowing one’s haplogroup was limited in its usefulness but fun to know what 'tribe' one has descended from.
What is relevant to family history is the ‘relative finder’. I have been told how many cousins I have, whether they are first - fifth cousins and I can look at each person’s listed surnames, some have listed 50 surnames and the areas of UK common to their family. If I have a 4th cousin on there and can see a surname on there that we share in the past, I can email them and ask them more. It also aggregates the 10 most common surnames from your ‘cousins’.
I think that it’s probably at its most insightful for people who are adopted or illegitimate, as they can find cousins and by process of elimination, sometimes work out who their direct relatives are. It is odd to log on and see that the number of cousins has grown to over 500, where they live and what surnames they’ve listed and put on a family tree.
Good to know your opinion on it!