I was waiting until I got home to address cam's response, but by the time i got home i saw your response too, so I'm gonna get this tag team!!
lets first deal with the analogy b/c we're parsing it beyond what's necessary. Yes!!! for any raid content you need a team avail themselves all at the same time to complete that content; while as a crafter (outside the FC shop) you don't need a team of crafters present all at the same time to complete any craft. The simple comparison was you need more than one crafting job to complete any useful gear (for example) and I liked those several classes as a team of crafters necessary to complete any meaningful craft, yes it's possible to be that team all in one character now that nothing is gated behind spc; but when there were SPC gated recipes you literally needed separate characters (a team of crafters) to facilitate creating all the crafts in game.
Secondly, addressing yours/camie's "independent vs interdependence".....you are being pedantic....so I'll be pedantic too LOL. Economy literally means interdependence and independence is the exact opposite of economy; it's not physically possible to be titled independent if at any time you trade ANYTHING (even if its trading products/services for gil......so now that we're done being petty....lets go bk to the bigger picture).
Of course having some level of independence helps control price points on goods and services, again I agreed having a lot of competitors that can potentially compete encourages "competitive pricing" (or better known as MASSIVE UNDERCUTS!!! LOOL). But image this real life analogy:
if everyone in the world was master certified vehicle mechanic; no one would ever NEEED a mech! You would still have mech services being provided though due solely to competitive advantages (this guy has a bigger garage than me, or this guy has the tools I need, or I just dont have the time today, etc etc). And also with everyone being a master certified mech it would be "hard" to overcharge on services: "how much you charging??? naw, that's too much I'll go to next door instead---oh, oh, now you wanna negotiation....hmm." In this everyone-is-a-master-mech World there would still be economic transaction occurring, HOWEVER IT WOULD BE COMPLETELY DUE THE COMPETITIVE ADVANTAGES.... you'd have to wonder how the economic activity in this made-up world full of master mechanics would fair... with most ppl being able to sit their cars/bikes/boats in their own garages and go to town!!
However in a world where everyone ISN'T a master mech, it would by definition require at minimum the same ppl to ppl interaction (MOST LIKELY MORE) in order to facilitate the level of repairs being done in the first world (the master mech World)---yes i'm assuming ppl dont all collectively decide "we aint getting shit fixed!!"
In the first world economy was a matter of CONVENIENCE, which is still a viable means for economy!! But in the second world economy is a matter of NECESSITY and it makes the interaction less elastic by definition.
If you force ppl to be locked behind a spc class (even if its just for a time) by NECESSITY you have to interact with some other character (even its still YOUR OTHER CHARACTER) to get the crafts you want. This type of interaction is less elastic than if everyone can craft anything and they choose to interact out of convenience (today I might do it myself. tomorrow I get this other guy to do it.)