I've been looking at how we've been using tags for things that are brand-specific. In my mind the vast majority of our tags should be generic, with specific brand names only used where specified in the question. I've, for example, re-tagged this and this question so they are no longer tagged
[full-frame] as the answers given discuss the differences between full frame and cropped sensor lens mounts, and are not specific to one particular brands mount or the other. This also means that searching for either of the tags reveals a list of similar answers, that are not brand specific. Obviously there will be questions that are specific to one brand or the other, but I feel we need to use the most general tag we can, so that questions are related across brands.
I don't think we need to include a list of brand names when we tag a question. Examples of this are these questions (1, 2) about raw file formats that list tags for all the main formats. What do we do when a new raw format comes along? I suggest a re-tag to just
[dng] in the cases I've just linked to.