Removing the Sisterhood would be a great idea and I'd be 100% behind it, but there's two things that crush the idea.
First of all, quite some people don't want their character to die. I'm not talking about people refusing a duel or people who don't want to climb a steep cliff; I'm talking about people who refuse to ever let their character die, even if they're in a terribly lethal situation. I do understand that you enjoy playing your character, and I do understand that you've put a lot of time in creating them, but if you don't want your character to die, you shouldn't put them in lethal situations. Do you want your fragile, elven hunter to live? Then don't kick a strong knight in the shins.
The second problem is the other side of the last problem. People who don't want their character to die, and who show this by keeping them away from dangerous situations, can still be back stabbed by some roleplayer who thought it'd make for an interesting RP. Sometimes, an inexperienced roleplayer can forget that online roleplays have to come from at least two sides. So when someone doesn't want their character to be killed, because they put a lot of effort in creating them, another roleplayer might overlook this and try to kill them anyways.
I know it might sound boring, but even if your character is a feared assassin, he should never kill someone who doesn't want to fight, and whose roleplayer doesn't want them to die.
So, if every single person on Hollowworld would make these problems disappear, then go ahead and remove the Sisterhood.