Several years ago I took the Martin factory tour. Much of the work is done by machines; they thickness the tops all the same with big sanders, inlay the rosettes, and cut out the outline with laser cutter. However, at one point there was a woman with a long and very sharp chisel carving the braces. She'd take a top off a cart load of braced ones, slap it down on the bench, and shape the braces very quickly with the chisel. After a few swipes with sandpaper it would get put onto the 'outgoing' cart, and she'd pick up another one. She was not trying to match the brace shapes to the stiffness of the top or anything like that; she had a model top in front of her and they were all supposed to look like that. You could argue that it would be more efficient from a production standpoint to cut the braces to shape with a machine before they're glued down, as Taylor does. However, the fact that that woman, and others like her, carves the braces by hand is a selling point for Martin: their guitars are more 'hand made'.
That's one of the differences in a really hand made instrument; we can actually take the time not only to carve the braces to work with the stiffness of the top, but we can even make the top a different thickness if we want to. All of this will depend on the properties of the particular top being used, and the desired sound and other characteristics of the guitar being made. When one person is responsible for everything they can choose the wood that will best suit the purpose, and work with it in the way that will best accomplish it. The more people that are involved in the process the harder it would get to realize that single vision, I think.
Otherwise, in most respects, the technology you use to do the work is less of an issue. Obviously each method of work has it's advantages, and can also set limits as to what you can do, or, at least, what you can do easily. A sanding machine is reasonably quick, and gets the wood to a uniform thickness more exactly than most of us can do it by hand. On the other hand, it might not be so easy to vary the thickness of the wood from one place to another, as you might want to do for any number of reasons.
'Sine scientaim ars nihil est'. One possible translation of that, as I understand it, is: "Without understanding skill is nothing". That woman on the Martin line is a very skilled user of the chisel (and the person who sharpened it is pretty good, too!). However, that skill in not linked with an understanding of how the guitar works, or the freedom to make changes in the bracing profiles to suit based on that understanding. The one-person shop maximizes the freedom to make those sorts of changes, no matter what technology is used, so long as it doesn't preclude making the changes you need/want to make. All you need is the understanding to make the right ones.