This a common scheme in many places/situations where allowing people the choice of what to do with their money is forbidden. In contrast to the ball-bearings, we can't legally establish a primary exchange of CCs for real money directly or indirectly afaik (if people treat them like real money because they are promised to be redeemable for real money the state legally treats them as real money and us as money transmitters). We can however accept CCs ourselves as if they were an equivalent amount of bitcoin.

One of my favorite examples of in-game currencies is QQ coin which became so popular in China merchants began accepting it. China came to view it as a threat to the reminbi and Tencent had to enact controls on its transfer.

In either case, CCs differ from most in-game currencies in that they are merely a stop gap for us, intended for minority circumstances, and we allow, prefer, and will incentivize stackers to use real money in their own custody/control. We'll do everything we can make CCs obsolete and in the longrun I think we will succeed at that.