Im agreeing with you here. Even though I dont use threatdowns I know how it can be beneficial. Just bacause you use threatdowns doesnt mean your dps fails and just because you dont, doesnt mean your aggro management sucks.
Im used to running without them so ive just learned to cope.
with tanks you run with often its not a problem managing thresholds. Watching the tanks aggro on boss helps too if they dont use voice. Challenging...engaging..etc..
As for what Astero said- while its true others can help with aggro, you shouldnt expect burgs to be full time provoking duty(traited/legacy) and the same with champs. On my burg ill provoke every now and then depending on the groups dps but not every 5 seconds. Im not gonna manage aggro so you dont have to.