Why do we need thieves??

[Bill Zebub]

I can see an argument for a general purpose skill monkey in a class system where most other classes are focused on special abilities and the like,

Doesn't that 100% depend on the design of the game, though? Specifically, what actions are defined such that anybody can use them, and which are defined such that you need to explicitly have that ability? Because really those are arbitrary decisions. Or, at least, there's a spectrum of "probability of success without training" with no demarcation between two distinct categories.

EDIT: Your point is still valid, in that however the designer decides to create the two categories, there is an argument to be made for a skill monkey. So maybe what I'm really saying is that the OP's title for the thread should have been: "Why do we need skill monkeys?" Because skill monkey = thief is true only for some games.

 

[Fenris-77]

I think this whole topic is very system dependant (obviously). Even if we keep our analysis to games within the OSR not every game has a thief. That said, almost all of them do have a skill-based class which is defined in part by opposition to the combat-based class and the magic-based class(es). It works well for that kind of game, whether you call them thieves or snot stacks.