It's not, but it would have been more efficient at attracting uncritical press a few years ago. But NTT moves at the speed of the former state telco monopoly it is and that's why this is happening only in 2023.
Isn't it sort of the same question regarding if it would be better to use an open source vs a closed source solution? This way all operators can be sure the profit is shared fairly, it's transparent. However it creates probably unnecessary data redundancy. It could also be pruned after a while.