Another possible use: I used threaded rod in the base of the workbench I built years ago. (And still use today.) My intent was firstly to eliminate racking and secondly to facilitate quick and easy assembly and disassembly as I had a boat re-building project on the go and would move all of my woodworking gear down to the boatyard evrey time I had a week to spare, then back home when I needed to go back to work. It worked really well.
The stretchers are dowelled but not glued to the uprights. There is a channel routed on the inside of each stretcher to house the rod, which then passes through the uprights and has a nut and washer on each end, (recessed.) The URL below shows a *very* rough sketch, which might explain it a little more clearly