You're welcome. The "full node centralization" has already been dealt with in the above link. Everyone was not meant to have a full node in the end. Just before he left, Satoshi was gearing up to implement "client only mode" as default, which would have used SPV and not stored the blockchain. Also already understood your point about RBF and answered it, even if my answer could seem a little convoluted or evasive at first glance.