During the Councilor Cruise event in 2012, when the ship docked in Veta they opened the brewery to give out free beer. There wasn't really a limit to how much you could get, so until it closed down people ended up with absurd amounts.
Yes, I think a year or two ago they also had an event during Alegarten to get Gunter drunk by giving him a ton of beers, I think part of that was to try and get rid of some of them as well.
I got mixed up a bit, the getting Gunter drunk thing is yearly it seems. But there was a one year only thing where they had a Beer Throwdown between Gunter and Angrybeard where you could only donate free beers to whichever side you wanted. Like a restock war, but to try and cut down on some of the numbers. I don't know how effective it really was though seeing as how many there still are.
To add to this, the Recycle Beast did ask for Free Beer as an item on 6/13/2013. So much free beer was turned in that we actually lagged the site. I have no doubt that got rid of quite a bit of the hoards; it would be cool if RB asked for it again. That would make a big dent in the current supply.
Free Beer was given out (I think at Alegarten) once since the Recycle Beast last asked for it, too. So because the Recycle Beast had asked for it once already, tons of people hoarded even more in case it was ever asked for again. I did, but I don't use an autorefresher so I only had patience for about ~2k but I still have most of those sitting in my vault, just in case.
I wasn't aware they released them a second time. Did they not learn from the first time around?
Apparently not :/ I want to say it was last year at Alegarten? I'm not sure but I know I didn't participate in the cruise (I had just joined like a month earlier and had no idea what was going on) and I had heard about the ping group for free beer at the Recycle Beast so I grabbed some the next time it was available.