I genuinely don't understand his fascination with Carrazo specifically. Don't get me wrong he's a 100% valid target for ridicule, it's just that he's... just a random fugly former cartoonist that barely anyone knew existed even when he was "successful" that made one show no one watched, got caught with CP, then dropped off the face of the planet years ago. That's literally all he's known for, being an unoriginal hack that pitched the same show 20 times and getting outed as a pedophile. That's genuinely all there is to the guy.
Like at least Skyler Page was actually involved with successful projects like Adventure Time and made Clarence, a show with an actual fanbase, before he was outed as a sex pest, and Dan Schneider was obsessed with feet to a cartoonish degree and had a bunch of power and influence. Kyle was so uninteresting that the only memorable thing about his entire career is that he didn't have one and he looked like/was a chomo.
I guess it's not much of a surprise that Joe is so lazy comedically that he would actively seek out a target so niche and detestable that he could avoid any kind of pushback by mocking him even if it comes with the cevat of 99% of people having no idea who the person he's mocking even is or how he relates to anything, but still.