75% of kids aged 9-12 in the US join these hangouts, and I imagine not being able to participate would be a Linux adoption dealbreaker for many.
I dragged out my macbook (as there was no Linux support) and it was ridiculously easy to make a 3D multiplayer game that millions of people could play instantly (sure, only a handful of their friends played my creation, but still - if you made something good, the audience is there!). It was also a great introduction to my niece on using 3D software - she loved adding tonnes of random stuff and moving it around into weird structures.
I've tried to make multiplayer games in the past, and it's a nightmare. Having a giant player base already authenticated, with all the plumbing in place - it's just a really fun environment to develop for.
I wish there was something similar (and as popular) for making "more serious" games.
Phantom Forces even had a sponsored event with Disney.
I would be interested to know if Unity LEGO Microgame aims that kid creators market.
Certainly not young children, who to the 50th percentile will lack the computer, as opposed to phone, needed to author a Roblox game, and to the 99th percentile, the developmental skills needed to program in Roblox Studio.