The minimum damage enemies can do to the player is 1 point of damage, not 0. That's not an example of durability negation, that's game mechanics of an attack always doing damage no matter what. That's the reason I linked the wiki, you guys are making durability negation out of a game mechanic.
Also, that's not being stubborn for not knowing that intangibility was changed to invulnerability. I'm pretty sure that was the whole point of Sans having intangible attacks in his profile, for still being able to damage Frisk. This is just invulnerability negation then, nothing about the frame attacks actually negating durability, especially when the attacks are supposedly done on the soul. Y'know, the true source of the dura negation for the undertale verse.