However the second part of that aphorism is "but some are useful". I have often wondered how much of IT/Programming is just sticking well understood pieces together. I remember 8 years ago wondering why we could not replace LLVM with a much simpler system that replaced all the manual optimization with a simple AI "optimizer" trained to transform simple compiled code into "optimized" code. I remember the consensus being that the AI system could likely not produce correct code reliably enough to be used. If AI cannot replace such "low level" code, then surely "high level" problems are widely out of reach. Yet people use it for "high level" problems. What gives? My hypothesis is that a lot of modern digital engineering is "plug and play".