Sure, but you also have to consider entities such as Muun wallet or Bitrefill which have tens or even hundreds of thousands of users. Impossible for them to build a relationship with each one. (I named these two specifically since they were involved in the above linked discussions on GitHub and the mailing list.)
Yes, indeed. I was referring to smaller businesses, which are more in number. Bitrefill, as a successful business, ought to switch to lightning.
Sure, but it wouldn't really achieve much if almost every other node continues to run opt in RBF and rejects all the replacement transactions you broadcast. Or more to the point, unless major miners update their nodes to start accepting full RBF replacements.
More nodes that have Full RBF means more chances
for everyone to establish connection with nodes that have Full RBF. Therefore, more chances for an attacker to take a user's transaction and hand it over to the miner.