I see amp modeling as both an advance in guitar sound effects as well as an approach to simulate the past.
Initially there were just gutiars and amps, and not much selection. Then more models of each came out allows some variation in sound result.
In the 60's stomp boxes came out and allow a guitar player to modify his sound with a small foot controllable unit. Over the years many different stomp boxes came out offering a range of sound effects from overdrive to delays.
Amp modellers are the next step in this process, where a single device (like a Line 6 POD for example) included many options for sound effects, all done with digital technology.
With a POD you can dial in a variety of amps and speaker cabinets. Where the advance comes, is that multiple parameters allow the user to customize the result. The end result is an almost endless series of sounds based on thousands of combinations.
Ed