What do you think of a system where there is no charm/charisma ect, but you have to rely on roleplay if you want to convince someone of your right?

What if diplomancy would be divided into various versions? For example, you need different knowledge and attitudes, if you want to diplomancer the dwarves than you would if you want to diplomancer the orks?

At what level diplomacy can't solve things? Or it should solve everything even if it resembles more to mind control than persuasion?