My answer to that group is that they can turn the debuff off.
The answer to that is that they can't because of the realm race (or whichever), but in that case, at least to me, it sounds like the interest of that group doesn't lie on the challenge itself, as much as on finishing ahead of others (which is probably just as fun for some people).
The problem is that realm ranking is important, even moreso if there're still realm 1st achievements to get. Not unlike in PvP, there is competition among hardcore and semi hardcore raiders. It's simply part of raiding, just like the challenge of killing bosses itself. It matters much to all those raids going for realm 1st-3rd. Also, realm and world ranking play an important role when recruiting.
This is not about being a special snowflake or elitists wanting the kills and gear just for themselves. It's about challenge. Raiders are challenged by both raid mechanics and other raids. The nerfs however take one of these aspects away. We have to choose between either the ingame challenge or progression. This is not a fun choice , because both are important for many semi-hardcore raids too (those that don't take 2 weeks off after a new tier release but don't need any help to down the bosses).
As long as there isn't any reward for clearing a raid the hard way (like an achievement or a mount), no one will care about it but for those who did it. There's no way to "proof" it somehow and going around explaining how you killed madness without buff isn't quite a fun thing to do. It's definetely a fun thing to do, but nothing the community would care about.
Lastly, I'd like to add that in fact, this system adds a fourth, heck, fifth difficulty level to the game. Heroic, heroic (nerfed), normal, normal (nerfed), LFR. What's the point? No one who is taking raiding halfways seriousely needs a nerf in DS normal. Normal modes generally are too easy, only heroic seems to be meaningful today. Why not put a little more emphasis to normal, make it more challenging, so that clearing it actually feels like an accomplishment?
