So for the first time ever, I was booted from a random group today (I usually queue to tank several heroics a week to try to 'give back' a little to the LFD community). Amusingly, it was in a 'regular' random heroic, and because I was wearing my kitty gear rather than a set fully optimized for bear - though I was tanking in bear spec and form, and I've tanked heroic T11 content easily in the same.
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What surprised me was that I got hit with a 30 minute dungeon deserter debuff, even though my early departure was not of my choosing. This wasn't a huge hindrance as I don't need the randoms, but while I can see this as a penalty for choosing to drop group don't see the reasoning on its application here.
I guess this just lends credence to the adage "No good deed goes unpunished."