Is there a community or name for this? If not, I'm going to call it #neverscript. I find the web works far better, more often, for me when SPAs and JS aren't used. There's something about minimalistic sites that's very appealing to me. I know it doesn't work for all sites, but a lot of the web could be improved by reducing the frontend bloat.
Using "vanilla" to describe a standard, unmodified and un-customized version of something is a very common idiom. This satirical website followed the convention, it didn't coin the expression. I don't think it's even jargon, it's just based on the meaning of the adjective "vanilla":
Lacking adornments or special features; basic or ordinary: "a delicious twist to a vanilla plot" (Ian O'Connor).
For "vanilla js," I can still have compilers, type checking, advanced ECMAScript 2019 features, local storage, webgl, etc. Without that understanding, you could qualify something as "vanilla js" in lots of different ways.
If someone said "vanilla c++," they might mean c++ without the recent language features, or they could mean the latest language spec but no standard library. Maybe it's still okay to link OpenGL but not okay to use a desktop GUI framework? Maybe OS frameworks are okay but nothing more? There's no communal understanding there that I'm aware of.
I personally don't think there's a market for non-js users. Most of the web is pretty broken without. I've never encountered someone in the real world who lives this way, even in the tech world. At most, someone will install a no-script browser plugin. That makes whitelisting and enabling javascript dead easy for the user. The only legitimate non-js use cases, IMHO, are for extreme political cases where you'd also be using TOR.
Boggles my mind how bloated and down right creepy the modern web is today.
A webcomic is a far cry from some main stream site, but it served as a good window into how others abuse their viewers with bloat and surveillance.
Only useful feature to me that javascript enables is comment hiding.