"Setting a limit" though would, if a known policy, pretty much make it a free for all. A lot of people assume, or expect, food and beverages on board, so probably won't put a Coke or two in their bag. Telling them that it's fine may well increase the minority to a majority and supplies could run short. "Free? I'll be having that then"

I can only remember one comment about someone decanting JW Blue, and one or two about filling a bag with Heineken.
Champagne would most likely be warm and flat before that got anywhere.....