Attributing this to the technology driving the browser experience is silly. You can make a brilliant user experience with React. You can make a terrible website with plain HTML.
The improvement comes from the change design, not tech.
You could argue that the constraints of using HTML-first (as they call it) helped them stay away from the bad patterns they were using before.
But you’re right: The user change came from fixing the design, not the technology used.
This is a lot like those bad resume bullet points where someone tries to claim an increase in business was due to their code change. “Increased visitor count 100% by rewriting website to be HTML-first”. Then when you ask them about that point they concede that the entire site was redesigned to fix some design problems or add a feature and that’s what drove the visitor increase.
JavaScript: The Good Parts by Douglas Crockford is a comically short book. React: The Good Parts would be shorter still.
Fun thing, TFA describes a kind of multi-page wizard style form that I haven't seen a lot anymore in the last decade or so. But when I did see it, it's always some dogshit enterprise system. Some Oracle product for expensing expenses last time.
The problem with those things always seems to be that they are slow in the middle of doing your task. Every button is seconds of waiting. Doubly annoying if you have to go back a step or two. The badly coded SPAs seem to be slow at the start. It takes a while to load, but once it's loaded its performance is usually okay.
As soon as you include a network roundtrip in anything you're opening up a Pandora's box of slow connections, slow DNS queries, network outages, what-if-the-user-is-on-a-train problems, what-if-their-IP-changes-mid-flow problems, etc.
Reducing the network calls in any app has upsides and downsides. It isn't really true that SPAs are faster to render (as your example proves) but rendering speed isn't the only thing that matters.
> Is it slow though? Like in practice?
The multi-page wizards? The ones I've seen were. Enterprise crap systems.