I'm going to disagree with the initial statement, for two reasons.
The first one is that the idea that the Middle ages were grim and serious is inaccurate. People in they day-to-day lives had fun with simple and more elaborate things. Yes, they made fart jokes. This is actually immersive, and we have loads of texts to prove that. So yes, some memes are annoying (like this weird obsession with incest and weird-looking characters) but overall, I'm also tired of medieval simulators trying to make us think that life was like a perpetual Game of Thrones scenario with death at the corner all the time.
The second one is that a historical game that takes itself too seriously is always really bad news for teachers and researchers, because it means more students who think that playing a game is learning about history. I know it's a rather egotistic reason, but nowadays we already have enough online content trying to rewrite history that it's an issue. A student with an appetite for learning because they had fun in CK, while realizing it wasn't the most accurate depiction of history, is preferable to idiots who think Total War Rome is a historical simulator.
And I would add a third one:
In CK2 we had lots of silly supernatural events that were leaning more towards fantasy than actual medieval supernatural stuff. In CK3 we get some jokes, but a lot of them aren't out of place for a medieval game. Like, the obvious reference to king Salomon in the court event would be understood by a lot of medieval people. Also, I'm not sure which fart joke you're referring to, but one of the most famous medieval farce tells the story of a man who substitutes his soul for a fart when the Devil comes to take it.
Comments like the one written here by cristofolmc reminds me of those people who actually don't know the first thing about the daily life in the middle ages, but are persuaded to be very knowledgeable because they know of some very serious stuff like battles and laws. CK3 may not be an accurate version of the Middle Ages, but it doesn't really try to, and often it gets the spirit, much more so than CK2 ever did.
In fact, the issue we have is that this community takes itself way too seriously for a bunch of nerds playing games. If you want history, then do history, don't play games.