[sinkasapa]

Right, these are exactly the types of claims we try to debunk in Linguistics 101. It is a horribly misleading article. If one wants to see if something about a language is difficult for human beings, I suppose one can look at the point in development that children master the concept. But even that can be misleading, since there are language internal factors that can lead children to pick up a particular aspect of grammar faster in one language than another. In English, noun-verb agreement comprehension is relatively late, but the same concept is comprehended relatively early in French, though according to one article, not necessarily in Spanish [1]. One can't simply look at a language in isolation and say it seems hard to me, so it must be universally difficult. Navajo may seem relatively easy to pick up if one already speaks an Athabaskan language.

1. https://www.sciencedirect.com/science/article/abs/pii/S00243...