Regulation does add friction. And it makes it easier for a parent to say 'no, you aren't allowed that app' (which you can obviously say anyway, but it gives you a very solid and non-negotiable reason to say no). Some children will find their ways round things, but a lot, if their friends aren't using a particular app, won't bother, or they will be the type of children who won't try and break the law.

Most apps and sites are terrible in terms of the parental controls they provide - they tend to be all or nothing. E.g. I'd like to have a group for our family on WhatsApp but I don't want my children to be able to join random WhatsApp groups and there isn't any way to have the former and not the latter.