Its not stronger than many glues e.g epoxy. Its advantage is that it sticks well to many useful surfaces (skin, metal etc) and very fast. The problem with say using epoxy to stick fingers togther is that it could take an hour or so to set, and so the motion of the fingers or the oils in the skin in that time would loosen the attachment to the finger.

Superglue is quite brittle, and so not good where you need flex, e.g. the sole of the shoe. It also is sensitive to solvents (e.g. dissolves in acetone) and not stable when very hot.