Earlier quoted context omitted.
I'll avoid getting into the whole discussion about people on slow connections, accessibility, etc., as I get the impression you really don't care about them, and just point out the obvious fact that everyone has JavaScript disabled whilst your JavaScript is downloading.
You'll avoid it, because you don't have any valid arguments. Slow connections are not a problem, because React is ~40KB and Preact is ~3KB. If downloading 3KB is too much for your network, it's not the fault of React, JavaScript or any web developer that you're gonna miss out. Also, server-rendered HTML would NOT be smaller than 3kB - in fact it would require MUCH more bandwidth since server-rendered HTML can't be ca…
The number of things this paradigm breaks, only to then have to fix them again, but this time by implementing them in JS partially correctly is just too high, for the average web dev to manage on the short time budget they get assigned in their day to day scrum managed job, where new feature requests and KPIs are more important than actual usability of their pages, and few people even properly test on multiple browsers, let alone screen readers and the noscript situation. It is just too tempting for them to use some component "someone else already made" "do not reinvent the wheel" etc., while constantly being discouraged to spend more time on making things actually work well.