TL;DR Yes, we do.
TL;DR++ I think this functional group warrants a new tag, hence I would vote for keeping it.
Usually I am a bit more hesitant creating new tags, but in this case I am sure there is no problem.
Quoting quite liberally from Differences between phenols and alcohols:
There is a fundamental difference between the two functional groups.
And a bit more literal:
[...] if phenols were classified as alcohols, we would basically be clubbing two radically different classes of compounds under one umbrella.
So let's not do that.
I have not done the MATT yet -- and I would like to leave that for someone else -- but I also think that this would not really change my opinion.
Currently there are 120 questions, that mention phenols in one way or another. It would be sensible to start adding the tag to the high scorers to give it a solid base. I believe that can be still done quite quickly, so that is also no problem. Also not all of these questions actually need the tag, so a quick skim through it should do well.
Obviously there should be a tag wiki and a usage guidance. I would like to refer that to the tag creator.
I don't see mistags as a problem. More often than not a question undergoes some kind of revision; adding and removing a tag is usually on the minor side of that. For this tag I am quite certain it will not be falsely applied, i.e. it will not be used for questions that are not about phenols. Many of the revisions that are necessary, are those for posts from quite new users. These often suffer from more severe issues. Once you know your getaround the community there are fewer issues. Therefore I don't see any real con for keeping the tag.