> and devex.  

Indeed, devex is the strong point of react. See this thread: https://news.ycombinator.com/item?id=43770579

  > But it's not like that  components are hard to build.

I really want to like other frameworks, but if I'd have to build a MUI(x) by hand, I'll accidentally pivot our business model to "component library maker" as a result.

I think we need to be clear about what scope we are talking about. A full fledged data-heavy B2B application, or something simpler like a web shop?