> I would never build a SPA with intercooler

and why is that? Though mithril.js fan here, but intercooler, kitty, unpoly - they look fantastic kit for SPA. These libraries just look like what Golang is against C++ and Java.

For the same reason I use React instead of jQuery. Kutty/Intercooler handle simple AJAX very cleanly but as the volume of data and scope of interactivity increases it becomes difficult to manage.

I mean question is when do you need a spa. Take my beloved online pivot table. The web UI state is very similar to the server state. For instance, if the user adds a dimension to the pivot we need to instantly feed that back to the server. So it makes sense to use kutty here because server and web state are pretty much in sync and why would you not leverage server rendering for this.

Most apps I work on deal with large amounts of complex domain objects which are constantly being updated. A recent project ended up sending an average of 1 request per second. Doing all this server-side is a non-starter.

This is why I build SPAs: binding a button to a fetch request is the easy part. Managing lots of data in an dynamic/interactive UI is where I spend most of my time.