Here's the thing. It's one thing for these shows to teach kids to count to ten, or to know their shapes or whatever. These are reasonably simple, straightforward tasks that can easily be learned via puppet instruction. But if you, as an adult, go to Stinky the Plant and Elmo for lessons on how to raise a child, your problems are deep and serious. They are not the type of problems that can be solved with a song and dance routine, however cleverly crafted.
I don't find the parenting lessons insulting, exactly. They don't make me angry. On the contrary, I think the makers of the shows are well intentioned. But it makes me feel depressed that there might be parents who need to be instructed in such basic matters, in such basic fashion, and that there are TV show producers who feel that they are the ones who need to provide this instruction.