I think that I just figured out why I shall use "are" as the linking verb within the context where "you" is acting as subject! Since the pronoun "you" itself is plural form, it has to be attached with "are" instead of "is"! If I, however, have to emphasise the singular meaning in terms of 2nd person, I can use the pronoun "thou" as subject followed by "is" as linking verb, although this kind of expression is not that formal! Attached, please find the screenshot cut from the Wikipedia page of "Ye (pronoun)"!