The "extra" jokes at the bottom of a page is a Ryan North signature. He started it in his Adventure Time comics, but I think it became most associated with him in his defining Squirrel Girl run. I assume it probably is an evolution of the "alt-text" joke that was popular in many webcomics. Of course, he doesn't do it in his "serious" work like Fantastic Four or his honestly stunningly good comic adaptation of Slaughterhouse-Five.
UPDATE: I picked up the first issue of the new ongoing series, and it does have "extra" jokes -- on every single page! Noooooooooo....
The "extra" jokes at the bottom of a page is a Ryan North signature. He started it in his Adventure Time comics, but I think it became most associated with him in his defining Squirrel Girl run. I assume it probably is an evolution of the "alt-text" joke that was popular in many webcomics. Of course, he doesn't do it in his "serious" work like Fantastic Four or his honestly stunningly good comic adaptation of Slaughterhouse-Five.
If I take a step back, I can see that they come from a place of enthusiasm. But I still wish they just weren't there.