Know several teams using it personally, and am "internetically" aware of thousands upon thousands of programmers than use it. Maybe do a GitHub search?

It's nothing more than a DSL for a templating language that finally puts the template for a component where it belongs -- along with the presentation logic.

I assure you, plenty do. Including myself. I had a very negative reaction when I first read about it (much like the article author) after 5 minutes it started to make a lot of sense to me.

I know that many people use React and JSX. anecdotally, I don't know any of them personally