I'm glad they have put the onus of social media platforms, however I think there is no feasible way to make this work short of requiring 100 points of ID be provided to your social media account to prove age. As much as I'd like to share that information with every platform I think I'll pass.
Further to this, how do you police that on something like the fediverse? Is @Aussie.zone going to shut down because the onus of checking IDs too much for a small social media provider? What about IRC?
I assume there is going to be a series of marches consisting of a million angry children and their parents protesting the loss of Minecraft and Roblox ..