The Allegan Rot mechanic kills a lot of people especially in the duty finder parties as Lemon mentioned earlier. Since this is easier and more efficient to some degree and somewhat easier to keep people alive people use this tactic. Thus, people stay alive, unless of course you have a bad healer, or you have bad DPS who aren't properly geared for the fight and can't DPS properly. Even then, the Echo buff being implemented allows for this tactic to be executed successfully every time, so people will continue to use it. Fortunately, as others have graciously mentioned, you'd be better off using a PF group to do the ROT mechanic. Personally, I think that it is helpful to know both mechanics, just my opinion and good luck on finding a PF group