The situation with A, B, and C (A regretful-murderer, would-be-victim, and absentee-doctor if I skimmed that example correctly) being resolved with OOC communication works on a MUSH because there is nothing stopping that from working. On a game where someone has taken the time to code critical wounds - and that's not limited to MUDs, there are MUXes and MOOs with injury code as well, you might only have X amount of time to find a doctor before Something Bad happens to the character, whether it be taking a permanent stat-reduction of some sort, or even death. In those games, the thinking is different, and I'll make the comparison thusly:
MUSH considerations:
"The doctor would be around and available to help this person, so we'll find the doctor though IC/OOC means or pause the scene until the doctor is around, and go from there, because the doctor's player can't always be around, but we also don't want Player B to bleed out on the nice new aluminum plate flooring tiles."
Code-heavier game considerations:
"Let's not fuck around with anything that could legit kill us until we have a medic on-hand." or
"The doctor isn't around (it is up to the doctor to explain why they weren't around. Maybe they fell and hit their head and were in a coma last night. Maybe they were somewhere on the ship that the people in a bloody screaming panic didn't think to check. Maybe they had on noise-cancelling headphones last night because A & B are notoriously loud when they're off killing each other at off-peak times) so let's do stabilizing techniques and CPR and elevate B's torso and deeply apologize for stabbing B in the chest and cry together and deal with the fact that B is now facing the rest of their character's life maimed/crippled in some way, or perhaps they'll die, but this is how the story turned out."
I can certainly see the appeal of having things turn out A-OK or at least more to your liking, every time something goes wrong. I just don't know that I find it altogether compels people to tell the best story they possibly could, but simply the most pleasant/convenient.