Sure. I used my pocket hole jig and screws to fix seat of a broken old chair. It worked OK. I used wood glue before putting the screws in, and the chair seems now very solid. It was not simple process. But it definitely has its uses on some applications as has been said many times in this thread. The pocket hole screws were under the chair seat, so they are not visible.
The old chair's seat had been made with 6 separate pieces of boards glued together. When the chair was stored in the shed, it had damp and cold, and the glue just disintegrated giving up the seat structure. Had to clamp the boards into the seat form, and pocket hole screws joined them.