Do we really need such a level of anonymity?
Well, id does make a difference having the option! An one thing is to disclose your private info to a centralized db, another is to disclose it to one person or two that you need to deal with to complete the trade. I guess SN is simply exploring options and trying to accommodate everyone's needs.
You should have a general understanding of how you plan to run a crypto-based Marketplace and be specific in what kinds of trades you aim to cover. See bitcointalk Marketplace, there is sections gor all kind of deals Collectibles/Goods/Digital goods/Services/Currency exchange and much more. Each section has expert members who assist all kind of deals even sometimes without an escrow garantee. I suggest you spend as much time as you can here and resume what and how you want to run this kind of services. Not that we didn't yet talk about scammers and bad people.
Thank you for the advice, each sectin has probably something to teach us. We might have then the wrong approach? We are monitoring what users are aiming to trade and adapt consequently. I assume BT marketplace has been evolving the same way? Or have these categories and subtopics been defined by the original mods since the beginning, deciding what users are allowed to trade and what is not?