D&D is merely a ruleset, a framework for a DM and their players to utilize in order to (hopefully) have a good time together. Usually the DM interprets that based on their current players and the campaign is rarely ever fully RAW in my experience. Nowhere in it does it say humor isn't welcome in its campaign nor systems, if the DM deems it so. Besides, humor is about as subjective as it gets. For example if you were to ask me, by that logic Bard shouldn't exist, as it's too humorous for D&D.
Can we stop mixing up subjectivity and objectivity, please?
I don't think we can. The imposition of an objective alignment system on subjective concepts is pretty much the whole topic.
Regardless of whether there is some objective standard by which Anubis will ultimately judge Thomas Jefferson to be a Chaotic Evil slaveowner, morality is subjectively interpreted by mortals, and that subjectivity of morality was subverted by the original D&D alignment system.
Maybe there is some objective standard by which the God of Humour judges things to be objectively funny or unfunny, but humour is subjectively interpreted by mortals. A system to impose humour as an objective truth would not make the game more fun in the same way and for the same reasons that the alignment system did not make the game more fun.
