Just to be clear, the Wikipedia list is simply trying to be exhaustive and points out which ones are a matter of dialect and what's just an archaic form. Think of it like a list that includes you, ye, ya, y'all, u, thou. Those are not different pronouns - it's the same word with variations for regions, time periods, medium. Don't take "you can just write 'u' when you are writing on an electronic device" as a formal rule.