Yes, but the process is automated with existing programs anyway. It would require a more elaborate ledger process, but it would take the form of a blockchain modification, at least as how I envision it.
If you are converting points into crypto, it would be no different than BTC or any other blockchain functionality today. The “private keys” belong to the end-user of course, until such time as the crypto conversion takes place on the other end (purchases).
Basically, points are paid to the aggregator via fiat, which is the current practice today. The aggregator then reduces the point value conversion by the margin needed to make the program profitable. This is translated into crypto value that is relatively stabilized, because the program is backed by a specific fiat value. The end conversion for purchases is accomplished by again converting the crypto balance to fiat, and the aggregator is then paying the merchants back in fiat. In effect, the whole process is a closed-loop system, with no outside merchants requiring access to the blockchain.
You are creating a debit card that, although paying out in fiat, is completely supported by a separate transaction network, independent of Visa/Mastercard. This is merely an additional card processing software on the merchant side of the transaction, much like we see today, with Discover, Visa, Mastercard, Eurocard, and Amex all being processed on one card reader.
Obviously, I have to work out all of the little details prior to developing the actual system, but as a closed-loop system, it precludes outside merchants from accessing the system’s end-user information. Program participants (reward programs) should have access to the customer purchasing habits and demographic data, yes. That is part of the benefits of being in a unified points program.
Edit: It was interesting to see that many program participants (end-users), as much as 50%, do not use their points from any reward program. It defeats the purpose of having a program if no one single end-user can acquire enough points to be used for anything specific. When you aggregate programs, creating a real dollar value for the end-user to be able to use, you now have real benefit that customer base can readily use at “all” program participant merchants. In effect, you have created a new, broad-spectrum economy, based on reward points. This gives other merchants the ability to have their own programs, becoming part of a growing network of merchants able to increase their consumer base, where before such consumer base activity was highly specialized by tightly-defined demographic groups.