Have you...?
> Have you tried coding an SPA with pure JS,
Yes. Lots of them. Vertical line of business apps, as it happens, so I can't provide links, sorry.
Public web sites are often not really applications, more like documents, for which no JavaScript is strictly necessary.
For internally deployed apps the cross-platform nature and lack of need for administrative installation privileges are considerable.
> perhaps jquery
Certainly not. There was a time when jQuery helped lazy developers paper over the chasm between Internet Explorer and proper browsers, but that time is long past.
> and raw AJAX?
No idea what that's supposed to mean. I think we've all moved on from XML.
> You need to be a lot better at JS which fights you every step of the way with its insistence on throwing silent errors at the last possible moment, likely as not 5 steps after you actually made a mistake.
Total rubbish. You're basically stating that you don't know how to code structured exception handling and never learned how to use your favoured browser's debugging tools.
> raw HTML+JS+CSS is not a pleasant experience if you are delivering a non-trivial application,
I'm fine with it for applications of whatever non-triviality you'd like to conjure. This is the baseline for web development. If you you can't hack that then you can't properly call yourself a web developer. And if you can hack it then you will understand that you really don't need third party libraries.
-A.