as a React developer, SPAs in general are overused. Most LOB apps could (and should) still be written in a backend templated language. SPAs should be reserved for applications (or even individual components) with advanced interactive features, ie a proper web app.
That's also my conclusion after toying a bit with those frameworks. You want to use them for specific pages ressembling applications, but you still want the main structure of your frontend to be defined server-side, using the most standard technology.
This lets you split your interface into more isolated components, and makes you free to use different framework depending on the type of interaction your page needs, as well as be able to update your site progressively.
yeah, for most web apps that are primarily regular CRUD+routing interfaces, you can/should use SPA tech to progressively enhance your more advanced controls. There are cases where it makes sense to build a whole SPA (I'm working on an in-browser editor that wouldn't work very well as a backend app, for example) but the vast majority of cases where React is used, it just adds complexity and challenge.
React/Redux hasn't been around long enough for its best practices to solidify in the general industry so you'll often find that companies that picked up React have a hodge-podge of incorrectly used technologies included because they didn't know the use case for Thunks vs Sagas, how to use Reselect correctly, whether to store any given state in Redux or a Container, and so on.
Enterprise apps are also a suitable venue for SPAs. You've got some developers coming from e.g. Swing, MFC++ or even Tcl/Tk, and for those doing every frontend bit in JS is closer to standard UI toolkits, instead of the constricting request/response cycle of old webapps (except those few that did some hacks with server-side continuations).
Also, in those cases a few extra seconds for the initial load or the general size of the application don't matter. It's all better than your average Swing application ("Challenge accepted", said the Electron developer).
Although this isn't something contemporary frameworks seem to aim for (ExtJS is dying, and that's good), you get close enough to desktop UI development with Vue/Vuex/Ant Design, Angular/AngularMaterial or React/Material-UI/Redux-boilerplate-reducer-of-the-week.
yeah that's basically the TL;DR of it - the more "desktop app" type functionality you need in your web application, the more SPA technology you're liable to need.
