Well, a little, anyway. That means a both the crafter and the seller have to know the value of the item in crowns or energy (which shift relative to each other anyway, so they have to know it currently), -and- the crafter has to have it available at all times. If either the crafter or the seller doesn't know the true value of an item, there's room to walk away without the second transaction - and because some money has changed hands, it's really now so close to a legitimate trade that staff disciplinary action is exceedingly unlikely.

Also this sort of player solution assumes that every new player -knows- to demand some kind of security before handing over materials. Even if there were an in-game bit of help about that, most new players are unlikely to read it or pay attention to it until too late. Well, I suppose the same is true of my promise items, hmn... but I feel like this sort of system would quickly become understood in a way that currency wouldn't be.

And nobody has ever asked me for currency to hold hostage - of course, I'm crafting for free for friends and guildmates, but ... a scammer would say the same, wouldn't he? 'I can craft that, no charge, just give me the materials, crowns, and energy... ' A scammer can also simply say he doesn't have the currency, and see if the target of the scam changes his mind. If he doesn't have the promise item, then either he doesn't have the recipe or has been failing to craft other promises, either way, something is clearly wrong there.

And of course, the promise item proves that the recipe at least exists, and hasn't been used falsely before, a guarantee that currency doesn't give.