The Scalaz vs Cats issue (and seeing what happens to them over time as a 'community judgement' on whether the CoC decision was correct, as in the article) is mu

The Scalaz vs Cats issue (and seeing what happens to them over time as a 'community judgement' on whether the CoC decision was correct, as in the article) is muddied further by the fact that Cats is different on a technical level too (it's not just a fork of Scalaz). Cats is more approachable than Scalaz. Whilst you could ostensibly see it as an extension of their CoC principles, I think Cats mostly just benefits from being much, much newer and so has more freedom and power of hindsight.