@OP, if you know FCoB already and cleared with mates, I'd bet you're fine without. PUG though may want Stoneskin cuz stranger-danger healers may not give you shielding spells at those moments when you really need them.

..
Just some added thoughts semi related.. ..(long Frontlines queue)..

Fracture is helpful for melee at lower levels when there isn't much of a GCD rotation

Fastblade 150 potency, Savage Blade 200 potency, Fracture 220 potency over 20 seconds. Rough math: 4560 Potency over a minute with Fracture (no clipping) vs 4200 without. Just under 9-10% DPS boost. At low levels TP starving isn't really an issue. Boss HP isn't that deep, and no one has costly TP actions yet anyway for AOE trash, and it's not like you'll pull an entire room at those levels anyway.

And Fracture/Stoneskin Tank Swaps... At/After tank swap MT can Fracture or Stoneskin to give the OT 1 GCD of breathing room on enmity.

It's not necessity, but it's a nice alternative to just standing idly by for a GCD.