There are plenty of Destro Locks that are breaking the numbers you're putting out. There are Affliction Locks higher, but if you're going to ignore fight mechanics and rely on your raid comp to increase your DPS? Silly. What would you have done if your raid didn't have those Arcane Mages to handle it? Rely on someone else? That's the point, you're saying the Destro is broken and non-functional while ignoring any scenario besides your own.
By the way, plenty of Destro Locks break 9k DPS. There are Destro Locks above 9k on all ICC bosses. So who cares? Top Destro Locks on Marrowgar are less than 200 behind Afflic. Check some WoL parses, doesn't take long to look up. Sounds like a broken spec to me all right. The difference between Combat and Assassination is much higher and no one seems to mind either and neither is called 'broken'. Seems pretty silly.
Also, read what I was replying to. That's what my arguments were discussing. Should take about 20 seconds to see I was replying to someone saying Destro was dead.
Anyway, have fun pretending Destro is better for 5s. All heroic trash is AOE bait. It all has ~64k health as mentioned before. Afflic and Demo are both better suited to it because they can AOE with as few as 3 targets. Destro needs 5+ for AOE to be higher DPS with RoF and 4+ with Seed. Demo is right now the best spec for heroics, there isn't any comparison to be made. You have Meta up for the entire boss fight and in many cases Immolation Aura is up for half, or more of the fight. 7k+ easily on bosses, 9k+ on trash. Destro is pointless in heroics. You'll get off Immolate>CB>Conflag then have to switch targets. With even a 3 pull you're doing that while Afflic/Demo chain seed for 12k+, on a 4 pull it's higher, 6 pull it's higher.
Destro is more competitive on raid bosses than in heroics, yet while you think it's broken for raiding, you think it's good for heroics? That's just silly.