That just makes this concept make even less sense. What do adults get to retire from the responsibilities of childhood and just make more babies?
The thing is this idea COULD work if you just completely embraced the absurdity of it and wrote it as if a child were writing it from a child's understanding and perspective. You could easily see a child thinking "OH YEAH? Well what if KIDS were in charge and went to work and adults had to go to school instead!?" You could get pretty funny and creative with that, and treating it as if it were a child coming up with this world you could easily avoid all the uncomfortable questions about the logistics of it all. Cause a kid doesn't know any better. A kid doesn't actually understand adult life or adult things.
You could have the adults just be big clueless oafs who like weird things like newspapers, bran cereal and waiting in line, who just are too naive to understand the importance of maintaining one's business relationship with their imaginary friend, or the value of jawbreakers on the candy stock market.
The other thing about people like Enter is they think they'll just pitch their brilliant idea to a network and get put completely in creative control because they're obviously a genius. Cartoons change so much from their initial pitch and pilot. Ideas get changed, characters get refined etc. People who think they're just gonna waltz into the industry with no clout, no experience, and no contacts like some genius auteur who networks are going fall all over themselves to hire are in for a painful reality check.