Another issue is the powers in tanks for example.
You have to "tag" enemies with damage to constitute participation. So, my Invuln tank with no damage in my aggro aura will be out done by fire tanks/scraps/brutes just standing next to the enemies. Yes I have foot stomp but its not a toggle that fires off ticks of damage constantly. There are other comparisons here too like willpower vs. spines and dark/kins vs emps and paindoms, not to mention MM in general.
Also, if it counts powers being activated constantly I have rage triple stacked without speed boost so does rage not count as a participating power like other non-damage powers?