I don't think it is a simple as she asked and they answered. Blondie explained how it is normally with her group of friends. Okay, maybe she has learnt that she will need to find a better way to ask these friends, but if they had of said, yeah bring a case of beer, a bottle of bourban or anything more expansive would everyone still think since she asked and they answered that she should have to be happy with the answer.
I don't drink anymore but if I did I would find it inconceivable to turn up for a party/gathering without a bottle of something. I haven't drunk for 7 years but I still get the urge to drop into the bottle shop to grab drinks if I'm on the way to see people.
I hate arriving at someone's house empty handed. Even if they expect nothing I still have an expectation upon myself to brinf something.