I'll reiterate: Residents graduating from residency programs at our "top" children's hospitals leave with subpar patient management skills due to a combination of exceedingly rare pathology and abundant presence of fellows. These places are excellent training grounds for fellows, but provide too much supervision to residents for them to develop independent management skills. And frequently the fellows are graduates from similar programs with a similar thought process of "well the resident shouldn't be managing that, they should talk to the fellow" and so there's no one asking the resident what their plan is, or why they want to do it this way and not that way.
I mean, we're in a situation in which the evidence points that graduating PEM fellows don't have technical proficiency at any procedure for a critically ill patient - intubations, central lines, chest tubes. There's a whole thread in the SDN EM forum here about how if you think you want to be a PEM provider to take care of critically ill children you should either just go for EM or do a PICU fellowship. I have friends from residency who did PICU fellowship at major children's hospitals and have said if they had done residency at those major programs there's no way they would have done a PICU fellowship because the resident experience was so lacking compared to what we went through as residents. No chance at procedures, no autonomy of any sort, basically just note monkeys for a month with a little bit of teaching that may or may not have seemed relevant. My own experience as a fellow at a top 10 children's hospital was similar (though I was deadset on the PICU and would have done it no matter where I did residency).
So if you're an attending at one of these places, watching as your fellows take more and more responsibility for managing patients because the residents aren't allowed to do anything, leaving them incompetent of independent management, what's the logical conclusion? More training! Fellows know how to do things, we need more of them! Or more accurately, create a class of trainees that you do actually place some responsibility on and when they graduate they can function independently and bingo, fellowship objective met.
Sadly, I don't know that there is anyway out of this spiral, short of a massive nationwide uprising by peds residents to demand more autonomy more akin to IM. Since that doesn't seem likely, adjusting fellowship structure (eg 1 or 2 year clinical fellowships) seems like the most likely way to stave off a terrible shortage of pediatric subspecialists.