Siguro to sum it up, amp sims are the counterpart of drum samples. Even if you had the most expensive Craviotto snare in the studio, but your client wants a 13x3 steel piccolo snare sound (which you don't have), the client would ask you to slap in drumagog or a drum module to emulate the sound, even if in real life, a real steel piccolo in action would sound much different (not necessarily unimpressive).