I have a 1980's Leightung dowel jig. Never use it, but the hardened bushings are great for lining a piece of plywood jig and using them to keep the bit vertical (and not chew up the plywood).

Dowels can be handy for joints where there is not enough width for biscuits/dominos, but damn if they don't have to be perfect for alignment since there is no wiggle room for adjusting.