Now other beverages are included in the scope of the site, do we need a beer tag?
It would be a bit of a pain to retag almost 500 questions, but it can be done with five users in at most an hour since the only thing that needs to be done is adding the beer tag.
A tag that general is probably not that useful. Beer questions that are about a particular type of beer (stouts, IPAs, etc) are tagged by style now, and we should keep doing that. I'm having trouble seeing the utility of also tagging them "beer", especially since we want this site to grow. That'd be a huge number of questions, right? How would you use that?
So, you might ask, what about wine? Yes, you're right -- that's going to cause the same problem later. (I hope you don't mind my putting words in your mouth like this. :-) ) Wine is newly in scope and there aren't a lot of questions yet, but in time I expect we'll see subdivisions there. Perhaps we should go ahead and start with red-wines and white-wines right off the bat.
Now some questions really don't care about the type of beer or wine; they're questions about storage or production or something else. In those cases we have other tags already. So there might be utility for tags like "beer, any type", but we should study our existing questions before deciding (and naming) such a tag.
Tag ontologies are hard, and on most sites I participate on, the tag set evolves, inconsistently, over time. Trying to organize all the things systematically is probably just going to cause you to pull your hair out.
Finally, when doing large-scale retaggings, please try to not break the front page too badly. It's better to either do these things in smaller batches so that they don't push new questions out of view, or announce in advance that we're going to bump tons of posts on such-and-such date so people will be expecting it.
I think the site needs a beer tag after all — not to retag all existing questions which already have reasonable beer-related tags, but to tag new ones, which need to be distinguished from questions about wine, etc.
To take a recent example, Is it safe to drink? is tagged storage but it is about beer storage. It's not about a specific kind of beer, so those more specific tags do not fit.
Also, it's now possible to be a user of this site without being interested in beer at all. Such a person would benefit from being able to ignore the beer tag on new questions.
