What is a disadvantage to a four-point cane when compared to a single-point cane?

No real disadvantage....however, it is harder to use at an angle, and heavier (when made of the same material). Quad Canes are very stable and reliable, and do not rock back-and-forth very easily, but both kinds have plusses. many people prefer the quad cane for a number of reasons, but a good, single-point, standard cane can be just as useful. It really just depends on your needs and perspective. I added a link down below so that you can see how many different kinds of quad canes there are.

Thanks

btlwgn98, cane collector and aficionado.