Addressing "Leechers"

So I'm sure this has happened to you once in a while and you may even have done it yourself but stepping out of the battle arena and getting locked out on purpose. Can we fix this so that people who do this (and yes I have done it myself) will not get credit for the drop from the boss? ex. Mhachi Farthings/Matter, and tomestones from bosses. They still have access to the loot from the chests but not anything that drops from the boss. I'm starting to see it too often now and this bad behavior and laziness needs to be discouraged.

I've never, ever purposefully got myself locked out of content as it seems completely counterintuitive to playing a game. I would go further & say that anyone who doesn't fight in a particular fight doesn't get a chance to roll on loot. I know that I've joined parties in progress for 24 man raids just as they kill the last boss, or as the last boss room is locked, and on principle I never roll on any loot as I didn't help in the fight.

Thinking about it, what's actually needed is a better attitude from the community, rather than any methodology of punishment. It's a shame that so many people experience feelings of entitlement.