Pretty much what Crash said on Fusillade. Melee sorc's bladestorm or Wraithsword(which feels terrible compared to Bladestorm even if you're phy build in any situation), just doesn't cut it against bosses. That just leaves us with Fusillade. It's still a viable kill. I play SSF. Killed Baal when I was running around in a full set, no fancy SU or SSUs then.
To be fair, it's not even a mechanically complicated boss whose difficulty scales with your toolkit. For example (Kabraxis vs Melee Sorc, fusillade) vs (Kabraxis vs any melee toon with only pure melee skills i.e. Melee Necro). On the flipside, a fresh TU 120 melee necro(carnage) kills Baal faster than a geared sorc.
Additionally, you don't want to bring minions in as Baal will spawn as many himself according to some random thread I read somewhere.