sometime self-custody doesn't even matter given the specific implementation.

As an example, imagine your airline issues "Airline Tokens" (each token represents 1 airline mile). Does that really matter if you self custody? they are only redeemable by the airline....soooo...self-custody is a bit pointless in that regard.

However, imagine all major retailers join together as a federation of "Award Points Federation" and your airline is a member.

The result is that it removes the single point of failure of your airline just deciding to zap your air-miles balance to 0....basically it becomes a beneficial tradeoff given the reality of redemption.