I also disagree that imitating someone’s style is impossible. Just like some people are laughably bad at imitating voices (I’m one of them), some people are shockingly good at it. The same holds true for musicians.
I don't think anyone is saying it's impossible; I'm certainly not. What I'm saying is that it takes a lot of practice and dedication to do it
very well --- well enough that it could fool someone into thinking it was the actual person. And that's why people say "it's in the fingers." That's just another way of saying that it's all about the player's technique, which takes time and practice to imitate well.
What we're saying--- I
think I speak for several here---is that the gear that's used to produce a "tone" doesn't do anything by itself. It's
always producing sound
via the player.
Take a Les Paul and a Marshall. We all have a pretty good idea of what this "tone" sounds like in our head. Some of us might think Guns N Roses, some might think Zeppelin, etc. But the fact is that even that classic rig can
sound different depending on who's playing it, even if all the settings are the same.
The equipment doesn't have a tone without a player --- whether that's an actual person or a robot. In other words, you can't hear anything unless someone is playing through it. Therefore, you can't separate the tone from the player.
If I played through David Gilmour's rig, and it didn't
sound like him, don't you think many people would probably say the tone was different? If you search many forums online, I'm sure you'll hear the words tone and sound (i.e., "Gilmour's tone" or "Gilmour's sound") being used interchangeably all the time.
To your analogy about mimicking a voice, I think it's a pretty good one. But I think you may be getting hung up by the word "all" in the phrase "
all in the fingers." IMO, when I hear that, I don't think they're saying that gear doesn't matter at all. I think they're saying that, to get the sound/tone exactly the same (or as close as humanly possible), the gear will only get you so far. The fingers (technique) are the crucial final ingredient. You said it's 5%. I would disagree that it's that unimportant, but it's subjective so it's hard to put an exact value on something like that.
But to use your cadence analogy in voice, I would argue that the cadence is
very important when doing an impression. It's one of the things --- another being accent (i.e. the pronunciation of the vowels) --- that separates the masters from the hacks when it comes to impressions. And I think that's what people mean when they say "it's all in the fingers." I think they mean that true mastery of said tone lies ...
ultimately ... in the fingers. That's my opinion, anyway.