By anyone who uses them as the loaded terms that they are.
Oh, how I would hope that "positivity" and "negativity" would be understood as relating to position and negation, like in your example! But in practical usage (as in "stay positive" or "we don't want that kind of negativity around here") they're semantic stopsigns for silencing voices that express unhappiness.
I think the term for a culture of only accepting expressions of happiness as valid, with the goal of suppressing constructive disagreement, is "toxic positivity".