As I've tried very hard to explain, it was mandated by technical reasons. We honestly didn't know any other way to do it. And, to this day, nobody has suggested any. I've explained why Bitcoins don't work, why proof of work doesn't work, why CAPTCHAs don't work, why some mechanism is needed, and why using XRP does work. Please, tell us what the alternative is. It must not require any central authorities once initial distribution is completed. And ideally, it would also be a way that makes it possible for us to make the system free to as many people as possible for as long as possible.