The Roblox experience also includes a huge existing player base who may come and play your game without having to install anything new on their machines. I'd say this social factor actually matters a lot for Roblox where many if not most games are multiplayer.

The only thing close is minecraft, which from what I heard already has similar restrictions on in game chat, plus other shady maneuvers from Microsoft.

Of course Roblox have more player, but does your child really need millions of players?

It's the same network effect with other megacorp, we could argue the same about X/Instagram/Mastodon, the question could be changed to: Do you want your children to be groomed to use closed source ecosystem from shady companies or do you prefer they gain experience in using relatively open ecosystem ?

Luanti let you make multiplayer games/mods too. For Minecraft there way to play outside of Microsoft sanctioned versions and servers.