That and in-person testing of equipment. When (pre-pandemic) I was buying a new set of headphones, I was able to go through different options, test out how they feel, and whether there are any significant sound quality issues. I prefer over-the-ear headphones, but have bigger ears, so it is hard to tell whether a set will be comfortable without trying them on first. To do the same with an online store would require ordering a dozen headsets, then navigating the return policies for all but one of them.