I saw a tag: best-practices
Isn't the entire point of meta to discuss what the best practices are? Couldn't we tag just about every meta question with this? What extra information does this provide?
I think there may be value in keeping such a tag (although there should probably be a proper usage guidance description).
First, I believe that there are questions which are pertinent to meta and do not fall well under such a tag. This is one example, and also this one, but I believe there are many others (and probably better ones to illustrate the point).
The tag best-practices seems to be well-suited for questions related to doubt about whether an attitude was the "right" course of action or not, where "right" may depend on context (it can be in an ethical sense, or simply to know if it was done under the guidelines of the site). Admittedly, this forms a huge chunk of meta as you mention, so the value of the tag is indeed debatable. I, for one, believe it is worth keeping.
Current usage is so mixed that I tend to agree it is currently not a useful tag.
In principle it could be a useful tag, if somewhat narrowly scoped. Martin quoted the description:
Questions about the best way to do something on a Stack Exchange site[...]
I would suggest to interpret this as it being for questions that ask in what specific way some action should be carried out especially if there are several plausible ways known to the asker, as opposed to questions about what action should be taken, or if an action should be taken, or how to do something at all.
I will agree that with moderate effort one can blur the lines, but I also think it is not completely meaningless as a definition.
To reiterate, I think it could be for questions that seek to clarify in which exact way something should be done in a case where one knows several ways to do it (or if one knows one way and wants to confirm it is perceived as 'best').
Thus it is in particular not for questions on what if anything should be done at all, and it is not for questions where somebody wants to know how they can do something at all.
Vote up this answer to represent the position that it should be removed.
An argument to support that might be:
The set of "transcendental" tags should be empty. That is, each tag should have a nice finite description + UG.
There doesn't seem to be a great way to define this in a way that is narrow enough for it to be meaningful and also sufficiently broad enough that it matches what people consider "best practices."