It's not just damage I'm talking about a perfect attack hits with the minimum no matter what Sinner boiling Stare can Just out right fail to hit,
Having stamina 8 is rare that is true but it's not like we go around trying to boil mortals. off the top of my head their are elder reds and whites and jades as well that can have a stamina over eight. Sinner Boiling stare can just not hit a target even if they don't or can't defend themselves in anyway. Even if by probability we are extremely unlikely to miss the fact probability plays a part at all is why it isn't a perfect attack.
Edit: For example
My understanding is that it works like this:
A regular attack:
1) you roll to attack
2) target rolls defense
3) if you have more successes add them as bonus dice to your damage pool and roll it
4) target rolls soak, subtracts successes from damage and adds the remainder to their health track
A perfect attack:
1) Roll attack.
2) Target cannot roll defense, add any successes from 1 to damage pool or roll it flat if you didn't get any.
3) target rolls soak, subtracts successes and adds the remainder to their health track.
SBS:
1) Roll Willpower against difficulty target's stamina + 2
2) Add successes to the target's health track as damage
In this context missing means failing an attack roll, wherever you sent the payload it didn't connect with the target and you didn't get to even try rolling damage. You can quibble about blocking/parrying being damageless hits, but in this case they're functionally the same.
Missing, failing to deal damage, and having that damage soaked are all different things and the distinction matters because they're independent failure points you need to get through.
SBS is a perfect that doesn't get to fish for bonus attack dice in exchange for bypassing the attack and soak failure points entirely. It shares the potential to botch a damage roll with other perfects.
As to the rest, I don't think we've fought anyone with stamina 8 so far. We've fought people with boosted soak, but not that resting soak at that level.