- Strict team separation (frontend versus backend)

- Moving all state-managament out of the backend and onto the frontend, in a supposedly easier to manage system

- Page refreshes are indeed jarring to users and more prone to leading to sudden context losses

- Desktop applications did not behave like web apps: they are "SPA"s in their own sense, without jarring refreshes or code that gets "yanked" out of execution. Since the OS has been increasingly abstracted under the browser, and the average computer user has moved more and more towards web apps[1], it stands to reason that the behavior of web apps should become more like that of desktop apps (i.e. "SPA"s)[2]

(Not saying I agree with these, merely pointing them out)

[1] These things are not entirely independent. It can be argued that the same powers that be (big corps) that pushed SPAs onto users are also pushing the "browser as OS" concept.

[2] I know you can get desktop-like behavior from non-SPAs, but it is definitely not as easy to do it or at least to _learn it_ now.

My actual opinion: I think it's a little bit of everything, with a big part of it coming from the fact that the web was the easiest way to build something that you could share with people effortlessly. Sharing desktop apps wasn't particularly easy (different targets, java was never truly run everywhere, etc.), but to share a webapp app you just put it online very quickly and have someone else point their browser to a URL -- often all they'll do is click a link! And in general it is definitely easier to build an SPA (from the frontender's perspective) than something else.

This creates a chain:

If I can create and share easily

-> I am motivated to do things easily

-> I learn the specific technology that is easiest

-> the market is flooded with people who know this technology better than everything else

-> the market must now hire from this pool to get the cheapest workers (or those who cost less to acquire due to quicker hiring processes)

-> new devs know that they need to learn this technology to get hired

-> the cycle continues

So, TL;DR: Much lower barrier to entry + quick feedback loops

P.S (and on topic): I am an extremely satisfied django developer, and very very very rarely touch frontend. Django is A-M-A-Z-I-N-G.