I am not sure if my understanding is correct about how commas must be used in case of a pronoun "you" and an appositive.
The wikipedia page on apposition says: And The Blue Book of Grammar says: So, from these two sources I gather that if the scope of possible meanings of the following appositive is narrower than that of the preceding identifier, then commas are not needed:
My teacher Jim McAlister was here yesterday.
Here the scope of possible meanings of
Jim McAlister is definitely narrower than the scope of
my teacher; therefore, there are no commas.
But what if the preceding identifier is simply pronoun "you"?
Naturally, I would think that "you" would always imply the number of people the speaker is addressing, but the following example made me think otherwise:
Here Rameses is speaking only to Moses, but his point is that all of Hebrews have been a big trouble, not just Moses. This example shows that "you" may not mean exactly those people who are being addressed or spoken to.
If so, then whatever identifier would be placed as an appositive right after "you" will always be narrower in scope of its possible meanings (than the scope of meanings of "you") because it will always be specifying which one of the possible meanings of "you" is exactly meant. Therefore, as far as I understand, in case of "you" and an appositive following right after it, commas are never needed.
However, I keep seeing again and again such sentences like:
You, the teachers, should bear a bigger responsibility.
You, Mr. Robertson, have failed to report to the captain.
I see such sentences in many authoritative sources and, as can be seen in the examples, commas are always used around the appositives in them. Why is it so? How does it go along with the rules of using commas in such cases, as described in Wikipedia and in Blue Book of Grammar?