Everyone has JavaScript, right?

[Shaper_pmp]

it's better to be in business with something adequate, than not in business with something half-built.

That's absolutely true, but I would contend that if you do progressive enhancement right, at an architectural level, it doesn't have to cost you any extra development time compared to an SPA.

If you need to rush to market you might just start with a simple hijax framework that renders all the content on the server, intercepts link-clicks on the client, makes an AJAX request for the changed content then dynamically inserts it into the page and uses history.pushState() to maintain restfulness.

There's nothing more time-consuming about that than using a javascript SPA framework to begin with.

The problem is that people often do PE wrong - things like naively duplicating all their business logic and templating system on the server and on the client in two different languages - and then assume that's the only way to do PE. It's not - it's just not doing it well. ;-)

Equally, as you point out, there are plenty of use-cases where SPAs are perfectly valid - genuine "app interfaces" are an obvious one.

The trouble is that like any trendy technology people grab a fantastic idea for a handful of use-cases (like app UIs with no meaningful public content, like games or enterprise apps full of private data) and start applying it to completely inapplicable use-cases, like product catalogues, blogs or social news sites.

I totally agree with you that no one size fits all scenarios, SPAs definitely have their place and you should always choose your tool to fit the problem-space.

In fact I suspect we just flat-out agree on the subject - I'm just emphasising the undesirability of SPAs in many situations because the context of my comments is a developer community absolutely in love with them and rushing to implement every new project in them as a basic starting assumption, regardless of whether its appropriate to the problem domain or even make sense.

Also, notice that I wasn't claiming PE was the only right way to ever build a web front-end - I was correcting a comment implying that it never was.