Yes that's kind of (but not entirely) my point. It's actually quite difficult (for a human) to lose a limb in a sudden accident without immediately dying. So it's exceedingly rare (~all historical civilisations) to be injured in such a manner, it's at least somewhat rare to survive such an injury (historically just about impossible), and even if you had flawless regeneration you'd be at a serious physical disadvantage (ie from an evolutionary fitness perspective) in multiple ways for an extended period. Meanwhile carrying said trait is consistently killing people off the entire time.