As someone at the "other extreme" end from web developers, and having briefly done some "real web dev" myself, I can easily see why it's so loathed. There are
immense amounts of churn. The continuing "appification" and bloating of websites with user and privacy-hostile crap. Reinventing ever-more-complex solutions to non-existent problems (remember the left-pad debacle?) Dogmatic cargo-cult thinking. Sadly, it's rare that a website "redesign" is an actual improvement instead of pure fashion-chasing.
(Whether that complexity is 'justified' is an entirely different discussion that, while no doubt interesting, has nothing to do with this person's post)
IMHO that has everything to do with it. It's hard to have any other opinion of web developers when you constantly see the large amounts of unnecessary complexity they foist upon everyone else. As I said, I worked in that space briefly, with others who had severe "framework envy", and largely see this complexity as being self-inflicted --- in some ways it was like Enterprise Java (another thing I did for a similarly brief time), except with much more churn. On more than one occasion I've had to clean up the mess they made by rewriting large web apps with simpler means, and the result was better by every metric (speed, memory, lines of code, etc.) except perhaps fashionability and job security.
I mentioned to some people I was learning clojure. Everyone was super into this. People started telling me I was really cool.
The author of this article must certainly not be in the same "tech bubble" I'm in, where telling someone you're interested in Clojure is going to be met more with neutral "what?" and "why?" reactions. However, I certainly agree with the title of the article: "signaling in tech is some fucked up shit".