Yeah the bureau makes JT65 look like a high speed data mode but it has its place. Out of the blue when you don't expect it an envelope shows up with cards from QSOs a year or more ago. The Old Guard tells me that was the primary way to QSL DX way back when. If you were a rich bastard you could afford to mail direct but it probably would get pilfered for the return postage cash along the way. (Some things don't change.)
As Derek45 said, you new guys getting on HF do get set up with your call districts bureau. A few envelopes and 'forever' stamps and you're set. It's part of the 3 legged stool of QSLing. LoTW, bureau and direct.
As an aside I haven't gotten any cards in a few weeks. This week a batch did come in direct. St. Helena Is, Burkina Faso, and a band fill from the Polish St. Vincent DXpedition. The Burkina Faso card is a keeper. Photo of the DXpedition operating location with a Spiderbeam sitting just outside a mud hut.