This is an interesting take. I have a somewhat orthogonal viewpoint -- rather than "heavy cognitive load", I think that going somewhat off-mainstream is good for attracting, on average, better devs. For example, it's likely that the average Haskell dev spends more time honing their craft than the average Java dev. The article kind of touches on this (e.g. FP "vs" the more popular OOP) with familiarity vs simplicity though.