Not only from the Zhentarim, also in tavern's like Elfsong, and why not already in Druid Grove where you find Wyll - I mean: they are training for combat. And other places like this. It is a need to have on the second playthrough I think. They must do something about that system, now that everyone had a chance to play with the premade Larian characters and get to know them.
The Withers system seems rushed and immersion-breaking quite frankly. I guess it's cool to have him in camp for resurrections (although I never personally had to use him for that) - but for hirelings it's just stupid and yeah, like I said; feels extremely rushed. I mean most of them don't even look cool in any way, two of them have the same facial tattoo and to be honest the "hide self" spell makes most of them look better which is just an absolutely bummer in a game that has so many cool features and details as bg3.