Look, I cant go into this for too much longer, I realized a while back that you cant really teach classic players when they are wrong.
15k hp does not care that in 20sec he will take 2-3k dmg. Its ignorable. By the time dot classes do their thing in SoD the front line is dead because of the lack of pressure and you are facing down Warriors, Rets, Shockadins etc, aka you are dead in a few seconds.
You can also not compare different versions of WoW. In Cata RBGs yes, dot classes were amazing. But it was much easier to mass spread dots, the healing is a lot lower, and dispels have a cd. None of these apply to SoD.
In Cata as well the BRGs are all flag control. Here everyone does AB. And when you die with full world buffs and consumes, you more or less lost the game because your power is insanely lower from that point on. So in Cata you die, rez, die rez and as long as you time the def and sniping the flag carry ? You can still win even tho you are losing fights.
Here if you lose fights its over. 20-30 sec for dots to do their full dmg and for you to dot 10+ ppl is going to take ages. You are dead, no questions. Again, this is why you have BG teams filled w/ Eles, Hunters, Boomies. Not because of dots, but because of cleave and direct heavy dmg. Starfire, Lavaburst, CS etc. On top all 3 can do heavy aoe.
Also, Mage has a lot more control than just sheep. But again I agree, there Mage also suffers in part from the fact that whole teams can use FAPs at the start and just be immune to Mage control for 30sec.
You dotting when you move ? Thats fine, tho Droods can Surge too, its a better option imo. But you dotting 1 by 1 ? As a Boomie ? You are griefing your grp.