Extending the scenario little bit :
So in few months every post on Steemit shows up with #qualitypost , since everyone thinks their post is the quality post.
Now the curators have so much work on their hands to find the really truely Quality post.
What do we do then?
Example:
I think this is a #qualitypost question :)
Thank you for this interesting question: I would not think that people dare to use the tag massively for low quality post if this niche is set up from the beginning with the intention that low quality posts are flagged. Nonetheless, if there is still many good quality posts, this would then be a luxury problem for curators. There choice would in any case be easier than in today's world.