I'm sure there's plenty of software that can block sites entirely, but that's a lot less useful.
And how much should I trust the popular products on a scale of 1-10? An OS setting doesn't need much trust.
> And with regards to account creation specifically, what do you see as a workable solution that isn’t defeated by a “pinky swear”?
I'll copy a different reply: "It's set by the administrator of the computer, so a parent can set it for their child instead of hoping their child is honest to every single individual site. That's the difference between a parental control and a pinky swear."
The idea of something like this isn't to replace parents, it's to give them a simple centralized tool. The parent has the admin account.