The question is, if people show up with characters that don't have a backstory, do they even need an incentive to stay together? In my experience that kind of players leans toward "we'll adventure together because we're the players." That makes this mostly a non-issue. The players that are likely to require an incentive are those that have a backstory and draw their motivation from that backstory. And that kind of player is unlikely to appreciate a meatgrinder that kills off said character before their backstory ever becomes relevant.

To me, at least, the meatgrinder seems designed to make sure your players are focused on optimizing more than roleplaying characters. Which is not my style but certainly works for groups that are into that.