They're doing lots of great heavy lifting to get effects and handlers into a production language, and I don't think it's fair to write them off like this. Yes, it's hard, but they seem to be making positive progress.
Sure, but at the end of the day what it means is 5 years into the effort OCaml still as limited threading-wise as it was at the start of the effort. And that is what most users (and non-users) care about in a world where 2/4 is your mobile baseline and where AMD's R3-3300G is expected to be 6/12 for $99.