There is an extremely steep learning curve on non goodie conjies too. Even if someone spells out for you how to manage the servitors it takes a fair amount of practical trial and error before you are able to really leverage them.

you hit the nail on the head though, if a conjie is able to get ready for a specific matchup then they can steam roll almost anyone.

But they do have a lot of points of weakness beyond bash them while they conjure.

Couple of things
-Most elementals hate being in water and will rebel if they are in it for long
-If a guy has a devil fleeing is a key point in happiness, try to minimize the number of times you flee and if you can get them to flee a couple of times they will likely turn.
-Hit archons early in a fight so they never sanc the conjie
-If you just want to drive them off kill the elemental
-There is an area where if you get the conjie to run through it his servitors will be trapped there
-Conjurers can't force their servitors to target a specific person so fight them in a group and rotate out the tank.
-Close to the above fight them at an inner guardian.
-its tough to hunt them at their conjuring spot but most conjies only use one or two gaunting spots, learn them and ambush them
-Knock out the conjie, kill his servitors, then kill him
-Conjies are absurdly vulnerable to fiends, more vulnerable then cloud giant villager