The goal posts have moved so far on what it means to be a little shit in cartoons that Bart seems almost angelic. I'd be more concerned if my children started aping Lisa's holier-than-thou idealism.
My kids have had no trouble screwing up and I try to help them learn lessons. There are many other shows that teach that same lesson without a cartoon cat and mouse filleting each other, dad drinking and bumbling around and choking their kids out.
I love The Simpsons; honestly I like Bob's Burgers more, but both shows live on a line between acceptable and unacceptable, like all adult cartoons do. They will find things that do the same and I won't know about it. But I don't spoon feed it to them.
I already give them all the vidya games in the world so they aren't starved for crude content. Also just living with me is all the crude TV-MA content they can handle. Mom and Dad are sort of fun to hang around (at least for Mom and Dad).
I am pretty sure kids can grow up perfectly fine without watching whatever cartoon. Really, no matter what cartoon is, the kids will be fine. Why do people attack others parenting based on nonsense like that? You don't even know age of his kids. Sometimes parent recognize influences that shaped him in a bad way and then attempt to avoid the situation for his children.
Bart is not archetype for screwing up and learning lesson, Bart never learns lesson. Bart is archetype of out of control brat. Which is fine and there is nothing wrong with that and that is precisely why people enjoyed the character.
I.e., Bart.
Edit: I'm not sure people realize I'm not the grandparent, or that I was directly quoting him to answer the question?