Keep forgetting to post this.

Blogs that have tags can be edited by anyone for some weird reason. Doesn't seem intentional because, for example, when an unregistered user tries to add a tag, they get this error message:
Some tags couldn't be added for the following reason(s):
*You do not have permission to create tags. You may only use existing tags.
Changes that did not cause errors have been applied.
However, if they just uncheck one of the tags and click on Save Changes, they're able to now add and remove tags freely.

Note, to the three people that have noticed their blog's tag has gone missing.. it uh.. wasn't me.