It used to be that only mechanical engineering was engineering. Now we have civil, chemical, electrical, et cetera. What is happening to software engineering is quite similar to what happened to other branches of engineering. The main difference is that the cost of producing software is usually dominated by design and labor costs (but not always). Before we had a grand tradition of aerospace engineering there were a couple bicycle manufacturers who strapped wings to their contraptions and tested them in a wind tunnel. The dawn of aerospace was all about fashion the same way you describe software engineering today: rock stars cavorting about the globe designing airplanes out of wood, cloth, and instinct, all to adoring crowds.
But the reason it seems like software is all about fashion is because you are browsing Hacker News. Hacker News is a fashion website for computer hackers, not unlike Wired but without its own articles. If you go look at actual software companies you will find a lot more reliance on well-researched tools and techniques. If you restrict yourself to places where other costs outweigh design costs, you'll see that it's much more familiar. Look at the software engineering effort for the STS, for example. Incredibly low defect rate.
The last time I looked (which was about a decade ago) the teaching of software engineering at the masters level seemed to be mostly concerned with process management, without any real equivalent of engineering's foundation in the physical sciences. In particular, the coverage of software design was mostly reduced to rules-of-thumb, some quality metrics of dubious relevance, and especially to documenting the result.
But the reason it seems like software is all about fashion is because you are browsing Hacker News. Hacker News is a fashion website for computer hackers, not unlike Wired but without its own articles. If you go look at actual software companies you will find a lot more reliance on well-researched tools and techniques. If you restrict yourself to places where other costs outweigh design costs, you'll see that it's much more familiar. Look at the software engineering effort for the STS, for example. Incredibly low defect rate.