it's cos you can lose pretty substantial amounts of progress to insta-kill coin flips.
yeah i usually keep a null dark/light around when i can get up to it but there's a pretty substantial amount of time when that's not an option
Honestly I've just been lucky that no enemies use those instant kills on my MC... He always seems to die to a lucky critical hit and then the enemy following it up by hitting the protagonist against with a heavy attack.