There are actually a lot you can solo, as long as you dont have to fight Champions or more than 2 Elites at a time.
Stealth, CC's and Dieing a lot help.
And yes, since you can buy most of the gear from vendors, they too dam hard and very pointless.
If you are Playing a Juggernaut or a Guardian don't even try.
Obviously you can't solo them at level.