I see tanking as a pretty simple thing to understand. Definition of tanking is not giving your best effort. Is it cheating ? Unfortunately not quite , its the closest thing to cheating without actually cheating. Is it a bad thing in this or any game ? Certainly Do I like it ? No but I can see the reason why some do it. Basically its the exploitation of a situation existing in not only this game but many games. Would I do it ? Not likely because I cant see the fun in it. Is there a way to stop it ? Yes I believe there is , other games have done it but its up to the devs of this game to identify the problem and deal with it.
Now move on guys , those who want to tank will tank until such time as the game devs deal with it , if they even want to.