The point is that all other engineering disciplines don't have enough design space to make a true mess of their projects. Software by comparison hasn't been limited in its design space since the first super computers started having gigabytes of ram memory in the late 1980s.
That doesn't mean that either discipline is better or worse, it means they are different. Other than math there is no other field which has as much freedom when it comes to basic design choices as software engineering, and math proofs are even more of a mess than software programs, to the point that pretty much every non-formally verified proof is wrong in some way.
Or to put another way: would railways be more or less complex if we allowed them to be embedded in a higher dimensional space instead of being essentially a 2d network on the earth surface? If you don't think so I'd like you to think about what a train schedule would look like on hyper graphs: https://en.wikipedia.org/wiki/Hypergraph