"If the user installs an extension that breaks the web, it’s the user’s fault, and the developers should not cater to them."

Likely so. My normal default is to browse the Web without JavaScript enabled, I've worked the Web this way since the 1990s. The reasons are:

(a) The web runs just so much faster without JS, also those jitters, pauses and delays caused by JS simply disappear. If people knew how much faster the non-JS mode actually is then many more would partake of it.

(b) These days, many web pages are enormous, it's not unusual to see pages that are over 7 or 8MB in size, they're so slow that one can just about have a coffee break before they load. Disable JS in one of these pages and its content can be well in excess of an order of magnitude smaller.

(c) Without JS, ads are almost a thing of the past. I don't bother to run ad-blockers simply because I don't have to. Without JS ads simply don't download.

(d) Without JS much of the online spying and tracking simply disappears. Those who want to track users can't help themselves from using JS (it seems to go with the territory).

(e) Without JS, annoying audio and videos don't start automatically. That's good because if I want to watch the content I can just copy its link to say NewPipe and have a much more pleasant experience.

(f) Without JS, pop-ups and messages such as those that ask for permission to accept cookies don't appear, similarly so for those asking for donations. Many web operators wait for a few seconds before displaying these messages, by that time one's already reading page content so the message is aimed to deliberately distract the viewer. Notable offenders are the Guardian and Wiki especially during its money drives, but there are thousands more just like them.

(g) Web browsing sans JS is more secure, there's less chance of receiving nefarious scripts etc.

It's not JavaScript that's the problem, rather it is web developers who actually abuse it to end users' considerable disadvantage. Turning off JS is my attempt to level the playing field.

People ask how I manage with sites that have key functions that require JS to work and without which the sites are useless. Several answers: first, sometimes I do have to turn on JS but it's certainly more the exception than the rule. To turn JS on/off I just hit a toggle button on the browser that invokes say the QuickJava add-on (and I never bother using 'cantankerous' browsers such as Chrome, Edge, etc.).

Second, when I come across a website that only displays a blank page if JS is disabled and or requires JS for some key function to work then I simply move onto somewhere else! If any web developers who adopt such practices are reading this then let me tell you categorically that there's nothing else that will get me off that site faster than that, in a sub-second I'm out of there. QED!

Third, people say I'm missing out on many web enhancements by turning off JS. Often that's true but in most instances I just do not want them. I find most pages that use these visual enhancements distracting and or outright annoying. When I read a book I do not expect everything on the page to be continually popping in and out, same goes for webpages. What's nice about HN's website is that its pages are static and they carry no superfluous junk. That's how I like it. In my opinion prerequisite training for web developers ought to be a compulsory course on human ergonomics (they'd then perhaps better understand what Web surfers actually want to view and then design their pages accordingly).

Finally, I'd add that I've noticed repeatedly over the years that websites with the largest size pages and those which include the most superfluous amount of junk are also the sites whose content I find least interesting. The fact is there's just so much content on the web that if 99% of websites were of the type that I've no interest in visiting then I still wouldn't have time to visit all the others in my lifetime (I can afford to be very choosy).

In essence, on the Web it's easy to set one's own rules and be choosy about what one views. And I'm sure the reason for why not more act as I do is that many have been forced into using the narrow webcasting as offered by the big internet giants. They of course all require surfers to have JavaScript enabled.