Well, if you're doing it for the sense of "this is MY home and workshop" and no real physical barriers, that certainly involves no complication . . . unless you've got a dwarf who uses more than one workshop, or you've got to remember to give your Novice metalsmiths permission to use the the Legendary guy's forge. For maximum efficiency, set up stockpiles for input/output directly above and/or below the workshop, with stairs right next to said workshop.
But if you're envisioning an "isolation capsule," where the dwarf sees nothing but his raw materials and maybe his dinner dropped down to him, and he drops his finished works to somebody else, that's a fast road to micromanagement hell. Consider how many times haulers move things. Now consider that you would have to Dump/Unforbid every single one of those things.
By all means, set up an area for your most valued craftsdwarves. Assign each one a home and workspace. Have burrows to keep the riff-raff out, and the enlightened ones in. Go ahead and make the whole zone infinitely self-sufficient if you want, preparing its own food for eternity . . . but don't seal out the haulers. A far better plan, in my mind, would be to give yourself the ability to seal out the haulers, probably by drawbridge, thus creating a "panic room" that protects all your most valuable dwarves in case of emergency. But if the haulers can't get your ☼weapons☼ to your militia, there's no point in having a Legendary Weaponsmith at all.