I think it ends up being more nuanced than that, with plenty of gradations of all of those factors.

If it means, "Literally nobody can know whether I prefer pads or tampons, and where I get them, not even the person I buy pads or tampons from", then I'm going to lean toward paying cash at some random drug store. A brick and mortar because getting things shipped to me requires giving them identifying information, and cash because it has literally zero fees and leaves no paper trail.

If I have to buy something online, then I already have to give them my name and address so I can get it shipped to me. At that point I may not care if my bank and the credit card processing agency also have a record of the transaction, because the info's already out there. At that point it's just a question of whether there are privacy laws that prevent parties from selling too much information or not - either way, I'm guessing 1 and 3 parties will ultimately fall in roughly the same equivalence class, on the privacy front.

Personally, I don't see a middle path where blockchain is preferable to either of those options. If I want complete privacy, then I don't want that transaction appearing on the blockchain, either. If I don't, well, might as well get some consumer protection.

Only the subset of privacy concerned consumers who don't want anyone to know whether they prefer pads or tampons will go out of their way to visit a random drug store.