Discord knows I'm an adult and keeps trying to send me "promoted Quests" to go use Roblox. That seems sketchy to keep baiting adults into childrens' spaces, too.
Roblox is mostly trash content form my perspective, but there are definitely gems in terms of playability.
I never really liked it because of the virtual economy aspect, but the only link between Discord having quests on Roblox or adults playing Roblox and kids is that's the majority of the userbase and therefor content, not that it's only for kids.