I think there’s a distinct difference between a community collectively deprecating something, versus individual members of a community deciding what will and will not be deleted. The first means the comments just fall away, while the second (and a statement of “we will delete your content it is not welcome here”) is actively off-putting not only to those who post that sort of content but others passing by who may be put off posting anything in case they unknowingly “break the rules”.
I don't see a problem there. “I won't post a jokey comment here as it'll just be deleted” is the system working. Much better than what has become the norm elsewhere: “delete if not allowed” which more-often-than-not means “I know this is not what is wanted here, but screw you and your rules”. They have explicitly stated that such content is welcome, just a little further away from the business end.