Bullshit. At 3, my kid could navigate to any content he wanted to, typically Spider-Man, Daniel Tiger or some train video in 5-7 clicks.
The path would always be clear, but the steps would vary. Click 3 would be one of those gross people who pimp out their kids to making toy opening videos, etc.
I would not see the same mix of suggestions when I’d use my account on that device. The journey of recommend content is the key.
I could accept that Google didn’t engineer that experience with the intention of targeting my kid. But I don’t find it plausible that they didn’t understand why that pattern monetized so well - YouTube is too good at printing cash. If they didn’t know, they chose not to ask.
Correction/Edit: I didn’t realize that google was fined for this behavior in 2019. Presumably it has changed.