The cost is not transmitting the js by wire, but executing it. 100k of js is very CPU heavy.
SSR does help though. But then there's this whole rehydration...
As I said in a prior comment, YMMV and some people love it. What you're saying right now does not ring true for me. But I'm not the kind of person who likes to pressure developers on how they perform their craft. I was just sharing my experience since you seemed to be in doubt about whether or not I was making it up. I'm not.
> React and Redux are under 100k minified.
Of course. But you're paying the round-trip on every page request, you're page-blanking every time--it just feels worse. For some things (where you expect documents--a news site or whatever) that's not the worst thing in the world, but the modern web is increasingly less document-based and more application-based.
And if initial payload is truly that much of a concern, Preact + Redux is under 5KB minified/gzipped.
And, FWIW, I have been party to metrics and user experience that shows that 200ms of latency can double your bounce rate. That 200ms of latency is not going to be coming from downloading react.min.js.
You may be right in some niches, but overall what you describe does not square for applications I build nor applications that my clients build, and I've been doing this pretty broadly for awhile.