If nothing else, you learn a lot about the rudimentary elements of a certain style of playing by trying to copy a particular artist. If that style happens to be electric blues guitar, then you're going to learn a lot about note bending and vibrato, for example.

Beyond that, trying to copy someone note for note on a particular solo may or may not clue you in to elements of that artist's particular signature style, like Stevie using those funky rhythm/lead chords, or Chuck Berry's kick-off at the beginning of "Johnny B. Goode," which is now a classic rock 'n' roll cliche. More rarely, you may get an insight into the creative process the artist used to construct that particular solo.

But there's where the benefits end. It makes no sense to try to copy every little nuance of phrasing and tone when the original artist is always going to be able to do it much better than you yourself can. Stevie sounding like Stevie is always going to be better than guitarist X sounding like Stevie, no matter how proficient guitarist X is, IMO.

It's enough to know how something was done - how a particular phrase was executed, what notes were played, etc. That's the cornerstone, then comes the experimentation, the 'english' you put on it to make it you're own. And you dream that this someday will evolve into your unique, individual style, for better or worse. Hopefully better.