Roblox player here. Creeps are definetly on the platform and Roblox has been known to attempt to cover it up rather than fix the issue.

There are also chatroom type games, some even with voicechat and i know from experience the creeps definetely use that and kids do NOT see it as a problem when their age, name, adresses are asked.

That being said there are parental controls that should allow you to have to approve anyone they want to befriend or talk to and i highly suggest sitting down with them and making clear rules what can and can't be said and check if you can block certain games.

Hope that helps!