You can't do that though. You are looking at guilds with 2-3 minute kills where you main DPS cooldown uptime is significantly higher and specs like affliction can roll retarded opening burst. Take these fights back down to average kill times and average players, and the gap is not what you see in that top percentile.
Imm, where nobody in the raid except the lock AoE adds, Sha where nobody but the lock AoE adds, Nazgrim where you start off with 3m dps that you ride all fight...being chain fed tricks, trinket rng... there is just so much extra above standard kills when you look at top parses.
Destro I feel is the most normalized spec between the 3. Its still dependent on opening burst, its still benefits from shorter durations... but the way you do dmg is not strictly front loaded to the degree of Demo and affs opening snapshot and is imo the most reliable pull to pull for the average player getting back into the class. The toolkit it brings is strong in all SoO fights.