The difference here is that these guys didnt stuck to the 'no shading, no anatomy, noodle arms, worm mouth' style and developed their own, adding that to well made humor that would be fun to both adults and children.

Honestly, the generic CalArts/Tumblr style looks cheap and lazy. You dont need anatomy, proportions, model sheets, shading, good animations.
Just draw the characters in wacky ways, add noodle limbs and a worm shaped mouth.

Of course, the show will be only about humor, so its easy to make the most non-sensical thing to be the plot of the episode, what about sentient sandwiches that shoot lasers?

And they dont even need to come with a new IP. Just reboot a new one as a comedy show! Worked for Teen Titans, PPG, Ben 10. Fans of the original cant complain, they arent the main audience!

TL;DR: Shows like this became the most generic and lazy thing that CN can show. Even Johnny Test showed more effort.

I get people like to call this the "CalArts style" because shows like Adventure Time, Regular Show, Gravity Falls, and We Bare Bears are recent popular cartoons by CalArts alumni, but I feel it's also worth noting the vast majority of people at Pixar also went to that school, and so did Craig McCracken, the guy who first made Powerpuff Girls in the 90s (so if anything PPG was "CalArts" long before the reboot, also Lauren Faust went there too), Butch Hartman, Stephen Hillenburg, the creators of Rugrats and Ahh! Real Monsters, and hell even a bunch of Dreamworks directors and animators went there.

Plus the creators of Steven Universe and OK KO graduated from art school in New York, and Gumball is made in the UK, so I dunno to me it feels unfair to just single out this one particular school when frankly a lot of cartoons people love come from it's alumni and I'm sure this art style is more rooted in something that goes beyond a single school when you've also got animators from New York and England using it.