I think this one would be more complicated than it was worth. If you really need to, you can flag. Who would this even notify? Pick a mod at random? Notify ALL the mods?(!)
I can't think of a use case for this. If two people said the same thing (first of all why didn't the second guy just upvote the first?), you can respond to them without having to bug everyone who's commented on the question. I can see this generating a lot of inbox spam as people who drop comments like:
Don't forget to frob the woodget!
are getting notified by the guy responding to a different commenter who said:
But Microsoft is better than Apple!
Because really, if we implemented this, how many people do you think would use it the way it was intended? I can see it being far easier to remember
@Commenters than having to, you know, remember peoples names.
No. Please no. I vote to close a fair deal on the sites I can, and on SO especially, I see many comments like:
@Closer why you close quesiton???? my qeustion is good u are terrble for not understanding it.
Usually they're not that nice, but I think you get the point. This would generate more inbox spam, but directed more at the user directly and not in a good way.