Initially, having a policy of only refilling the establishment's growlers may have been based in the idea of increasing brand loyalty. But as soon as a couple of places broke away from that policy, most brewers realized it was better not to require the glass have been from their establishment
I had a growler filled at Rockbottom last summer. They only fill their own growlers. So, the bartender put a Rockbottom sticker on it.
