...but you have found the more accurate guess-data.
Pinterest have presumably done well with Google's carousel that shows image search results at the top of the list.
I am not sure the HN crowd is target demographic. Who here is looking for a new outfit to buy and wear? Who is wanting inspiration for some 'infinity band' tattoo?
People here just end up on Pinterest wanting images for projects, no intention of pinning boards together.
Why does this happen?
Pinterest have built a body of content that is essentially evergreen and well documented as far as images go. Nobody is interested in last week's news but images don't have this problem. Hence they get the image search results traffic.
Beyond that they do have their regular crowd looking for inspiration on clothes, home trinkets and what not. The search result blessings keep them relevant even if nobody outside the target demographic is actively using it.
