Unfair dungeon deserter

[Saneko-ragnaros (Saneko)]

Deserter debuff in LFR isn't working as intended

Queued for an LFR, killed boss 2 and 3, LFR finished. After this re-queued, since I missed the first boss, killed boss 1, looted and left… (There’s no reason to do boss 2 or 3 again, because you’re locked out of loot.) Guess what? I got the deserter debuff. I don’t think this is working like intended, there should not be a penalty if you have defeated every boss in there.