`mempoolfullrbf=1` should be set in `bitcoin.conf` by default

[Peter Todd]

Over 90% of hashpower is mining full-RBF now because it's common for full-RBF replacements to pay quite high fees. Some of the reasons why users run nodes include self-soverign fee estimation and block explorers: both those use-cases are improved by accepting and relaying common fee-paying transactions that miners do in fact mine, as you have a better understanding of what fees are being paid, and of course, block explorers running on Umbrel devices can show those transactions. Notably, both https://mempool.space and https://blockstream.info switched to running full-RBF quite some time ago to be able to display those transactions.

Users of course can continue to turn it off if desired. But on balance I believe the default should be on for typical Umbrel use-cases.

Bitcoin Core doesn't seem to be interested in changing the defaults, nor do Bitcoin Core members seem to be interested in explaining why. They already made two releases recently without changing the default, even though a supermajority of hash power have adopted full-RBF. But that shouldn't stop us from doing the right thing for Umbrel users.