That's largely because a lot of developers have made the devil's bargain of replacing standard web stuff with badly re-implemented JS versions of same. People did it because they could, but never considered if they should.
See most of the ecosystem around React, for reference. It's idiotic that things like URL management are done in Javascript. Or form controls. I guarantee that if we stopped doing this kind of stuff, JIT wouldn't matter.
To some extent this is just saying "developers will depend upon the performance given to them", and that's true, but it's also true that as soon as things like V8 and Node appeared, JS became ubiquitous. Pandora's container, if you will.
The problem is not url management. That should happen just once or twice during the life cycle of a page. If it takes 0.1ms or 1ms doesn't have any impact on the usability.
One of my problems was that I wanted to show data in the browser. It is a convenient delivery platform, after all. However, Chrome (and Chrome in particular) has tremendous trouble displaying large pages. A 400x400 table takes a long time to render. I could solve that in JavaScript. I had to, really.
So, as practically always, the problems stem from a combination of factors, and bad programming definitely is one of them.
That's largely because a lot of developers have made the devil's bargain of replacing standard hardware and OS primitives with badly re-implemented C versions of same. People did it because they could, but never considered if they should.
See most of the ecosystem around modern systems software, for reference. It's idiotic that things like memory layout and bit-level hardware management are done in C abstractions. I guarantee that if we stopped doing this kind of stuff, compiler optimizations wouldn't matter.
To some extent this is just saying "developers will depend upon the performance given to them", and that's true, but it's also true that as soon as things like compilers and standard libraries appeared, C became ubiquitous. Pandora's container, if you will.
> See most of the ecosystem around React, for reference.
I've never used React myself, but what I've heard about it makes me question my own sanity. So are you going to tell me that instead of just updating the DOM tree directly I'm going to apply the changes to my data, then pass the entire model to the framework, which would then diff it with the previous version to get the changes back out, it would then call my functions that return components, and it would then diff the virtual DOM to find out what changed, and only then would it update the actual page? Why the fuck would anyone ever want that? What's so hard about simply changing the innerText or inserting elements or whatever?
Oh and now Google and Apple are insisting that this is the way to do UIs in native apps as well, with Compose and SwiftUI respectively.
The way the front end developer community seems to largely encourage learning top-down isn't helping either. I'll forever remember that one guy we made a small project with. He learned React but had no clue what "send a request" and "pass a parameter" means, and I had to explain him how to use XHR.