With Viscous Venoms and Doomblade, 40% of even mutilates damage ignores armor. So the only abilities that have to 100% go through armor are Ambush, Shiv, and Fan of Knives.
Garrote, Rupture, all weapon posions, Envenom, Crimson Tempest, Sepsis, Bone Spike, and Kingsbane all ignore 100% already. So depending on your parses, something approximating 70-80% of your overall damage won’t be effected.
Considering how much good stuff there is in the trees, it’s just not that great for sin to buff 20-30% of our damage by 30% considering alternatives. Just like how Seal Fate was essentially baked in for sin for a long time, that was baked into Sub for a long time. For them it’s huge as the percentage ratios are basically flipped, and massive portions of their damage are physical. Even with Shadow Blades dealing extra damage as shadow, that extra damage is based off of raw damage. So with big Evis crits, that 30% bump also gives a 30% bump to the shadow damage blades adds. It’s a core part to sub but just doesn’t really add much value to Sin. Outlaw can make good use of it though, and with Shadow Dance and Ambush talents they can spam ambush over and over for some nutty damage during Blade Flurry.