This is no more exploitative than someone trying to make it big on Youtube, Twitch, or Spotify and gaining zero traction. If the content someone creates on these platforms doesn't capture an audience, the hosting platform doesn't generate any revenue and neither does the creator. It's completely free to produce the content (minus your time) and the platform hosts it for free, even though 99% of it never receives any…
For adults, I agree. But this is squarely aimed at kids and they haven't got the life experience to see these problems coming or deal with them appropriately. If it were aimed at adults, but kids wanted to try, too, like Youtube... I don't have as much problem with that. But the target audience of Roblox ads is kids and always has been. It doesn't seem at all fair to trap kids into this ecosystem, sell them the thing…
That's what parents are for.