I've been using ClojureScript/Reagent for about a year now and all this JS tooling talk goes way over my head, I haven't needed to use any tooling other than lein cljsbuild for a while now, and it's glorious. If the Clojure community / ClojureScript was more approachable to beginners I think ClojureScript would be taking over right now.
Install OpenJDK: http://www.azul.com/downloads/zulu/
Install Leiningen: http://leiningen.org/
Create a new project and run it:
lein new reagent myapp cd myapp
lein figwheel
Once figwheel starts, you can edit src/cljs/myapp/core.cljs and any changes you make will be reflected live in the browser without having to reload the page. Now consider what you'd need to setup to get the same thing with Js/React.
I think the problem is that a lot of people are already familiar with Js and tooling around it, so integrating more tools piecemeal doesn't feel as hard as diving into a whole new ecosystem.