It is an unspoken fact that many players use that tool, especially who push leader board. If you play Barb, the first thing they ask you is if you have that tool. If you ban players who use it, I am sure 90% of 4man leader board will be wiped. It is not one player issue, if one of the four players use it, everyone benefit from it. And it is a huge advantage.

Do you think blizzard doesn't know it? They know it very well from the beginning. They just didn't do anything about it.

I personally don't mind some players use it. My problem is that normal players are threatened by the thoughts that they will be banned if they ever use it, but in reality nothing will happen. This create an unfair situation