I think if you asked any woodworker if they used biscuits for alignment purposes and not for strength they'd disagree with you. One could use screws to keep the butt joint together yes but there are a lot of cases where you don't want the screw showing. How then do you join 2 pieces of wood. There are a number of ways, dadoes, rabbits, dovetails etc. Biscuits is going to give you a very strong joing, a lot stronger than just butting 2 pieces of wood together.
Pocket screws are great but you really should only use them places that won't show, because they really aren't very eye pleasing.