That idea did cross my mind, however with the current way that posts get sent to notifications, there are already use and posting issues which would only be amplified were replies to become a part of our notifications.
I think the reply button is somewhat effective. It it too much to say @whatever their name is? And won't it clutter pages a bit if too many people use it?
@above Why should posts be hidden? That defeats the boards' purpose of creating a public forum of discussion. We can use profiles and/or mail for more private discussion.
Now that the button's seen its fair share of use, I will say that I personally find it somewhat annoying when I have to look at not only a post containing two or more nested quotes, but successive posts following that pattern. So it would be appreciated if forum users could not go overboard with quoting chains.