Reciprocal nitpick: That explanation of category is pretty weak and cannot be applied universally anyway. In many cases, gender assignment is completely arbitrary, and the article pretty much admits that. For example, in Croatian, table (stol) is masculine, while chair (stolica) is feminine, which is completely arbitrary, and both are inanimate. There is no rule in Croatian (or other Slavic languages that I am aware of) that categorizes gendered nouns for any reason.