If you have a compositional system, such as a programming language, you can use category theory to predict its behavior, in the same way that if you have a symmetric system, such as particles in a box, you can predict its behavior. In the former, maybe you prove that your programming language "can't go wrong"; in the latter, maybe you prove your physical system "conserves energy". (Or, do both at once: https://conferences.inf.ed.ac.uk/clapscotland/atkey.pdf). In any case, the point of category theory is to model compositional systems, which may or may not be worthwhile in any given context.