So even this "plain text" site still transfers ~98 % bloat and just ~2 % content.
its more around 90% JS, 10% content
After the first page load (with scripts cached) its around 87% content (unfortunately they don't seem to be caching CSS)
The question was why a pure-text non-interactive website needs any javascript at all.
* Generate a HTML/DOM based on a template and data.
* Lets you efficiently update that DOM based on updates to the data and/or model (this is it's killer feature).
But if you're just going to do the first thing (generate a HTML/DOM), you don't need most of React's feature set, and you certainly don't need to push heavy JS onto the client.
For those cases, a much better approach (for both clients and SEO) is to just pre-render the DOM/HTML server-side and serve that without any need for any javascript client-side (which is what the similarly named module "Preact" does).