I think it's important to remember that for a lot of people, this is all new. They probably expect the brewery to provide the sort of experience you're describing and likely wouldn't understand why their behavior is problematic. The scenario you describe is something I see all the time at wineries. People expect to be able to ask questions about the wine they're trying, and to be able to discuss what there is about the wine that they like or don't like. That can take a considerable amount of time, and is particularly annoying at a wine tasting festival (where there can be long lines to sample a particular wine). It's annoying and rude (IMHO), but fortunately it's fairly uncommon. I still don't have a problem with breweries providing complimentary sample pours in such a situation (despite the inconvenience).