True, cascade can be dangerous, but omitting it completely seems like a bold move — it's just a use case for cascade is very limited.
BEM is simpler to use because it's just a naming convention and doesn't require any tools (reBEM is just a set of optional helpers). It's also simpler to debug because with css-modules classNames are mixed with generated hashes, and with BEM you can clearly understand who is this className belongs to.
I agree, that BEM can be used without any tools. And it is his benefit. But in this article you use so many tools for them, that CSS Modules become more easy.
Compare:
1. You have helpers in JSX and CSS.
2. With CSS Modules you will have helpers only in JSX ;).
It is for some people. I'm not telling that css-modules are bad in general, it's just nice to have an alternative. I know some people who are talking about css-modules as an ugly hack (though I don't agree with them).