Watsit said:
The main purpose of the tags were to be able to distinguish between animations like post #4798565 (obvious motion tweening for head/arm/etc movement) and post #4443977 (obvious redrawing for head/penis/etc movement). A lot of people have a strong dislike for the former style of animation, even if there may be a few redrawn frames of animation here and there, but are fine with the latter, even if some movement is a result of "tweening".

But making them mutually exclusive under all circumstances makes it impossible to find posts that do utilize both, for those interested in that. Complex blacklists exist for this exact reason.

After all, tags aren't just for blacklisting.

The line is hard to draw, though. Maybe we should open a thread about this.