But, SpongeBob doesn't continually insert things into its episodes that force you to wonder about those kinds of things, and even if you did, the possible answers aren't as world-breaking and horrifying as the ones you'd come to in GA. "Who delivers babies in Bikini Bottom?" We've seen the hospital and doctors before in the show, we can figure that out."Who does SpongeBob pay rent to?" Probably just some landlord character that hasn't appeared yet because the writers haven't had a story that requires him, but if this character ever did appear, the world won't break as a result of his existence since we've seen other business owning types since the show's beginning.
SpongeBob is also an episodic and wacky cartoon with next to zero continuity and no deep "lore" to keep track of. Growing Around is not like this. He wants it to have a continuous story with real consequences that changes from episode to episode with an established world that has its own full history to keep up with. To put it a way he'd understand, this is like if someone criticized a plot-hole in Bojack Horseman and the response its creator had was to claim that Family Guy contradicts its older episodes all the time so it shouldn't matter if Bojack does it too.
For most of the questions being asked for GA, the only possible answers are extremely dark and disturbing for a supposedly happy children's show. In GA, we have parents dying of illness, and talk about wanting to do pandemic stories. Enter has established that disease and death are tangible threats in this world. Kids have all the jobs, this means they are the ones providing medical care. How does this work when they have no schooling or training? Did Molly's mom die because a toddler didn't know how to perform medical procedures? The audience is going to wonder about these things because he's written in plot-lines that necessitate these questions being asked.