I think you are cherry picking.
There are plenty of examples in the modern web of terrible React/etc implementations but that doesn't mean the approach in itself is bad.
If the creators of React can't get it right, then what hope is there?
https://krausest.github.io/js-framework-benchmark/current.ht...
It's also possible to use htm with Preact for developing without a bundler if your target users support ES6.
It was super ugly, but it did the job. Now it's super ugly, but it steals my focus at every opportunity, refreshes parts of the UI I'm about to click, or has select inputs that love to play hide and seek with my cursor. It's a UX nightmare.
I must say their new payment system is nice. But boy do we have to suffer when looking for something to buy now.
Unless I'm missing something, it's "optimal" for a site to have many split files. If their JavaScript were 1 file, a change to a single character would mean the need to re-download every bit of JavaScript. Instead, with 96 files, it would mean 95 of them are still cached client-side and only 1 is need of downloading.
The website features didn't changed in between. It's basically a pagination + a search based on radius (so DB related) + name (so DB related) + categories (so DB related).
The complete website could be build in pure HTML + CSS and a bit of JS + Ajax to refresh parts of it.
But no, it's build with ReactJS, and it takes seconds to search a simple item on it.
To compare, just try the same search on the Dutch equivalent, MarktPlaats, https://www.marktplaats.nl/. The experience is way snappier, way lighter, the features are the same, and it's just HTML + CSS + a bit of JS.
We made a mistake with React/Vue/Angular. And we should really go back and stop using those frameworks.