Game does not allow blacklist while in a dungeon. I an not even sure what the point of this post is, it is like you are trying to defend reasons why we can have it when we know it is not happening.
Yoshi-p addressed your "counters" for number 1,2,3,4,5,6,7, and for number 8, that explaing would not matter, see what yoshi-p said, so this suggestion is a clear no, there is no point in trying to counter AmemeAmeklin's postNaoki Yoshida: We do not plan on offering official support for voice chat. To explain that decision, the idea of talking directly to other players with your own voice and making it a requirement to do so will not necessarily be a good thing for beginners and new players and many will see it as imposing pressure or causing them unnecessary stress.
I am personally a veteran online gamer so I completely understand the importance of voice chat but if we were to make it an officially supported feature then there is a chance that some players would start to demand that others use it just because it is an “official feature”.
Of course, we will not be prohibiting external voice chat via Skype etc, so individual player communities can still sort out their own preferred means of communication!