That this disclaimer needs to be written shows that this USSD-based solution is less than ideal.

With Machankura being a custodial wallet, there are risks that we know very well (back-end systems hack, rogue employee, shotgun KYC, rugpull, etc.). With Machankura using a third party USSD gateway (Africa's Talking), those risks extend to that third party (and to the telecom networks for each country as well). And finally, the mobile phone devices are not secure as well. Rarely are feature phones "locked" requiring a PIN, or otherwise secured so that anyone who grabs the phone cannot spend the bitcoin from the Machankura account for that number.

There's also regulatory risk. Some of the countries where Machankura is supported are hostile to bitcoin (e.g., Nigeria and Kenya). It would take only one "memo" sent to the telecom providers by their regulator and Machankura gets blocked in that country.

That being said, this low tech solution can be today used for receiving (and sending) remittances, P2P trading, for paying merchants, etc, without requiring KYC, and in a peer-to-peer manner.

Many will receive their first bitcoin on Machankura, and then progress to where they use a device where they self-custody bitcoin or use platforms with less risk than they are exposed to with Machankura. But for those with only a feature phone today, there is no alternative, so the benefits (of being able to receive some funds and then spend those funds) likely outweigh the risk (of potentially someday losing access to the account's balance).