Yep - the author is very opinionated and it's good because it works really well for his workflows/usecase.
I'm with you though, personally react is a acceleration mechanism for me because I often find existing well built components already. I don't built the same thing as the author though.
I haven’t found too many issues with loading React and Babel from a CDN. I find React easier to read than straight HTML/JS. I find it more annoying to code in but seeing what state is needed in what components is a pleasant reading experience for me with single file tools.