Why make it simple for miners/swimming pools to prioritize transactions out of band when there’s an choice for RBF and CPFP the place a miner/pool has to incur price in sats? It appears to me that Bitcoin Core in any other case does not wish to encourage out of band transactions however why present an RPC technique on the similar time?

The prioritisetransaction RPC was launched again in 2014 to assist miners who needed to incorporate a transaction of their mined block that maybe was paying a decrease charge charge than competing transactions. One doable use case that was speculated upon in that pull request (#1583) was “captcha-solving as a substitute for charges”. As with a lot of the Bitcoin Core code supporting mining I believe it is not used a lot at the moment however Core usually needs to be fairly conservative in eradicating options in case it breaks somebody’s software program someplace.

Relating to supporting out of band transactions this RPC does not present any assist for receiving transactions bypassing the P2P community and Bitcoin Core mempool guidelines. Merely assist for prioritizing the mining of specific transactions acquired by means of regular channels.