Seems to me that adding a tag like that would just facilitate brigading.
Remember there are things like fallout equestria
and other community developed storylines for which one or two people arguably can claim creation of. It is not unusual to get requests to remove images that aren’t approved by the original creators of the stories because they have what they feel is ownership of the entire property and anything created by those who work in those alternate universes.
This is not just about one oc, it’s a very expansive issue that really affects a lot of different kinds of images.
And I don’t think adding a “I don’t like this” tag will help these situations, especially if it is construed to convey some sort of actual ownership of other people’s work.
For me, copyright seems like the only way to handle these kinds of situations in an environment where we have millions of users, 107,204 unique OCs, 148,942 unique artists.
Adding slippery concepts like “does the person who created the OC like this image or not” doesn’t feel like it’s helping.