Your quoted poster was not comparing Demo to either of the 2 other warlock specs, so I am not understanding why you launched into this big explanation about why afflic/demo suffer more.Since when? With ~25% of your DPS coming from that monster DoT called your pet/guardian, I hardly think the spec is immobile. Affliction has to stand still to cast their filler, Haunt, execute and Unstable Affliction. Demonology has to stand still to cast their filler, HoG, execute and Immolate. Affliction has an ability to refresh Corruption (already an instant cast), Demonology has an ability to refresh Immloate (saving them one of their immobile casts). Both trees can keep Immolate/UA up with a Fel Flame if they're forced to move.
If anything, you could make the argument that Demonology suffers less on sustained movement because they don't have the risk of Shadow Embrace stacks falling off the target. Affliction's stronger spell DoT damage doesn't offer any extra mobility. Demonology can cover that damage with their significantly stronger pet that is essentially just a set-and-forget DoT. Hell, losing your HoG pet buff is hardly as bad as watching your Haunt debuff fall off, due to movement.
Where's the mobility problem for Demonology? I'm not sure you've really thought this through. When the pet and guardian were for absolute shit and 40% of Demonology's damage was coming from Soul Fire under the effect of Decimation like it was in ICC, then I'd agree it was less mobile than Affliction, but I wouldn't agree that assessment is correct any longer.
---------- Post added 2011-10-10 at 10:50 PM ----------
Top AoE if you have all of your cooldowns available and juggle a pet. Every two minutes we can put out a big burst of AoE, but there are other classes and trees out there that can consistently put out more AoE for significantly less effort.