I would ban miserable people whose only joy is making company miserable.
I don't mean everyone has to be jolly, some years are heavy, some people are suffering grief, sometimes your just not 'feeling it' etc... but those who actively insist on being invited to others Christmas JUST to tear down everyone else joy can feck off.
My step dad was always like that. Sat grumpy, snapped at everyone, ungrateful for presents, wouldn't let anyone have fun, slagged off anything christmasy, turned anything and nothing into an argument (even if you 'breathed too loud' while we sat in silence) and would start taking down decor half way through the day declaring Christmas is over. I just don't get and never will get WHY?
I have had shit years, I remember feeling broken the first year after my pregnancy loss (after 6 years of infertility) knowing I should have been holding my newborn but I still soldiered on. I wasn't a great upbeat source or entertainment, I spent a lot of it alone but I didn't 'ban fun' for others. I still bought gifts, put up decor, was polite when seeing people and got through it for others.