I find myself wondering if support doesn't really help crafting a little. The repair vendors offer support, after all; that would make no sense if the support didn't effectively increase your level a little (since repairs don't require special skills or facilities!) Now, "it makes no sense" doesn't mean it wasn't put in the game that way, and obviously there had to be a general-purpose facilities person in each city SOMEWHERE, but making it the repair vendor is really dumb unless the support has some effect on repair...
To be completely honest, I've wondered that myself. The thought occurred to me that maybe it's for the HQ gear that everyone is saying takes a "higher" craft skill to repair. (I don't think it takes higher, I just think it has a higher chance to fail, much like a recipe that recommends Common facilities has a higher chance to fail than a recipe of the same rank that doesn't have that recommendation.) And the reason I bring up that as an alternative purpose is not to say it proves or disproves anything. It's just that as long as my results suggest very strongly that the facility support makes no difference unless it's recommended by a recipe and there are rational alternative uses for things like support from the repair NPC, imma stick to my guns about the benefits of facility support until proven otherwise by hard numbers.
There's also the fact that crafting in FF14 is a lot more complicated than it is in 11, much less other games, because of the gear dependence. Clearly all that gear's doing something. With a brass head knife, a pretty decent set of cotton crafting gear, basic support, and level 13 leatherworking, I was able to put together eight dodo leather synths with only one fail (though I ran into instabilities pretty often). Judicious use and abuse of fulfillment and preserve helped me get through. Doubtless in five more levels it will be a much easier synth, and I'll be shooting for quality instead of finishing with 10 quality and 10 durability and saying "whew!" But it's possible way below where it really ought to be...
I started making dodo leather around rank 12 with the bronze head knife and my current array of crafting gear (cotton gear mostly, assault sallet for BSM/TAN). It was painful, but I needed the straps/spetches so I stuck it out. Rank 14 was a bit better. Went back yesterday at rank 15 and it was ******* painful. And then when I had a mountain of dodo leather (about half the size of what it might have been minus the fails) I could have made a lot more spetches are grit my teeth and started in on vamps. Bored or frustrated...very little in between with that choice.
What we really need to do is to have people write down their crafting results. Not just "I was level 13 and crafted dodo leather 9 times, 1 fail", but with all the trimmings. What was your Control stat? Your Craftsmanship and Mag. Craftsmanship? What phase was the moon? Your elemental stats? Get enough data like that, and you could start running statistical regressions to figure out what had some influence and what didn't. (On the other hand, combining information from two people would be rough - if one of them is just better at the mini-game, or at least paying more attention when they craft, that would show up in the numbers too... Of course, a proper regression would demonstrate that as well.)
That would be awesome, but I'm not expecting it right now. It would require vast amounts of data and you can only do so many synths at one rank before you rank up and then you're on to a completely different data set. I would imagine it will happen in time, as will most things with the game.