MW3 has linear maps, zero recoil 2-3SK guns, and streaks that continue after you die.
You have now been proven wrong.
Seriously, Support killstreaks come up again? In the time it takes to get a Stealth or EMP, a good Assault streak user will have got a Pred, a Reaper and probably an AC130 - giving you a load more kills than the Support user who has to use his gun (or cap objectives) to get there.
I've been running Support recently when playing MW3 (there's a few titles I 'need'), and my KDR has been dropping, which means that Assault is just as much of a crutch - for padding the KDR.
Basically each Killstreak group has it's uses and if you can't recognise that then you're bad.