"I can tell something bad happened here" is way easier.
If you upload videos of kids and you're sitting back and letting paedos write this weird shit, you probably shouldn't be making, let alone uploading videos of children.
Just as if your community has an above-average number of people calling for the lynching of Muslims. Or quacks suggesting you can cure cancer with alkali diet pills. You let this stuff stick on your videos, it sticks to you and that attracts more.
Pushing this onto the uploaders forces them to think about what they're doing, and whether or not they really want to build that community.
In my mind it's the Broken Window Theory [0].
It's Google's house. Google's windows. I think they need to take more responsibility for cleaning up.
It's not the creator's fault if pedo's show up and comment on their stuff at a scale they can't possibly control.
There's another side to this coin!
There is a part of me that asks "Why are parents uploading pictures and videos of their children to the internet for the public to ogle over?".
The cynical part of me says "What did they expect to happen?"
It all comes back to money though... Google have had this problem for a while but their bottom line wasn't threatened until recently... let's face it: They don't really give a shit until money's involved.
If not, it's like saying you can run a forum, but you have to moderate the whole thing yourself.
And again, nobody is forcing you to enable comments. If you can't handle the workload, the arguments, the very worst of humanity, etc, just turn them off.
Why is that so wrong?
I understand that it's often hard work. I understand that they might want to be making videos, or product-placing, or whatever it is any given creator wants to be doing, but they're the people at the hub of their own communities.
They should have some responsibility over the conduct displayed there. And if they don't want that, they can host it themselves somewhere else, or disable comments.
Honestly, I feel YouTube would be a lot nicer place if the standards required weren't just the channel owner's. Plenty of niches are way too happy to foster the the next /b/.