This article is from 2016. The OP probably should indicate that in the title. As far as I have skimmed read the article, some of the claims the authors make have already been resolved in Julia, and I haven't used the language yet, but I will soon in the next couple of weeks.
Indeed, and while there is plenty to still be worried about, a lot has been addressed, too. Further we are now starting to see the pay-off with amazing algorithmic innovations being implemented in Julia.
We have working code to code automatic differentiation:
