Mixing humor into serious communication comes at the expense of authenticity. It's difficult to know what an author really means when they mix attempts at humor into the writing (and this is often deliberate, if someone makes a particularly spicy political remark, it's usually in the form of a joke, in order to shield from potential backlash). Overall it's a style of writing that feels sophomoric and insecure, as though the message itself isn't enough so there's a need to crack jokes to compensate. This successfully distracts from the message you're trying to convey, ... at the expense of clarity.
Only if you're authentically humorless. ;-)
You sometimes find texts where you get the feeling the author almost expects a sitcom laugh track over the post, and funnies are crammed into every available crevice.
I read a really interesting book* about the topic a while back where the authors delve into why humour works and how to find a style of humour that works for you. Unfortunately there are places imo where they fall into their own trap of trying too hard, but honestly it serves to prove the point.
* https://www.urbandictionary.com/define.php?term=Street%20Jok...