I'm not saying you're wrong. I'm just giving my opinion

Having grind a lvl 74 warlock/cleric, I can only say it's a great solo. And parties that are worth your time are practically nonexistent.
In all honesty, debuffing every single mob takes way too much time, and when you grind the way I did (Dots, run next mob, Dots...) you need healing to survive, unless you have a really good set

Edit:
Kinda pointless argument here, the question was if these builds could solo.
And yes they both can.