How to prevent guild hopping

I just had a crazy idea which if implemented could change the face of WoW guilds forever, and make guild hopping a thing of the past: What if when you left a guild, all the epic gear you got in raids was automatically taken off from you, and put into the guild bank. You keep all crafted epics, PvP epics, and badge loot epics. But everything that dropped from a raid boss you only got because of the guild, so why should you be able to keep it when you leave that guild? I bet that would stop people from searching for more advanced guilds all the time, always setting back the guild they left behind. What do you think?