Initial enmity generation and player bad habits.

[Mardel]

Funny, the problem I see is trigger-happy DPS that can't be bothered to use Quelling Strikes.

Sadly, I've used quelling strikes, left off BFB/Barrage while waiting for my next dot rotation and still pull threat after the tank has shield lobbed. (In PF/DF) I mean my bard isn't doing that much damage at the start.
Typically the tank isn't following up their initial hit properly. Now if I blow all my CD even with quelling I can't expect every tank to hold threat during that- which is why I try and delay that portion in pf/df situations.