I agree, canned responses are ideal if the play has to be unsupervised. Friend codes were frustrating though and a ton of people just posted them online where strangers could see them anyway.
If you believe your social interactions should have come from strangers via video games then that's abnormal.
Counterpoint: because my mother met her husband online in a chatroom, I spent most of my childhood talking to strangers. I was groomed online multiple times online. I was also sexually abused at three schools by teachers. A bunch of people me and my friends met off the internet were not who they purported to be whatsoever.
I'm still getting therapy in adulthood. I know what I'd have rather had happen.
It was a parenting failure for me too after the divorce of my parents.
Where there's the means to talk to kids properly, you'll find predators. That's a given.
It's also bold to assume that these are children playing Roblox on Linux, when they are in all likelihood actually adults.