This is true. I think everyone sits somewhere on a sliding scale of what they'll allow. For example, I can't think of even the strictest DM who, if the person on first watch failed to spot a group of ambushers, would have the sentry be garotted and the rest of the party murdered in their sleep with no response, even though that might make sense in that situation. But then, I also can't think of the DM who would send parties into combat and literally just have the enemy attacks bounce off and do no damage, either.The connection from "the world appears to exist independent of the PCs" to "character death" seems... exceedingly tenuous to me. People, even those who live physically risky lives, fail to die every day. In droves. The world operates independent from them, but they still don't die.