That's more like when you have large store or something like amazon where people sell also new products and they know all details about them.
Yeah, you're right, however this also applies to some niche community marketplaces. Especially when dealing with
collectibles and the enthusiasts involved in those circles. These people definitely know all details about their items... and then some. (You might have heard that many collectibles are actually kept in their
original packaging to retain value... hence bringing up the UPC code).
Also I can't really see why this feature wouldn't be useful for example on a second-hand DVD/Blu-ray marketplace of some niche.
As a longtime collector myself, I'm currently setting up a community-driven info database for certain niche collectibles, also exploring options for a suitable marketplace platform fitting my needs.
Since you didn't immediately dismiss the idea completely, I'm seriously hoping you could give this a bit more thought while we're at it, I believe it could turn into an excellent new plugin and could be a real game-changer for some Osclass users.
Some more info on my use case, hopefully not TLDR... I try to emphasize the key points:
There are easily 5...10 essential non-changing properties for a typical item (depends on how much subcategories are utilized), to go into custom fields.
That's
a lot of typing and selecting if you're going to list a number of items... especially when using a phone to do that, which seems to be a permanent trend in the world today, effective method or not.
When having a
master product table, in many cases listing an item could be as simple as typing/
scanning a barcode (querying by UPC and accepting the suggested result), then
adding a short description and item condition. The barcode scanning method is actually already available in many apps targeted to collectors, so I don't see this as a far-fetched idea at all.
However it should be possible for the seller to search other custom fields too. Only then if nothing found, the option to manually fill in all the listing details would be used.
For the site
admin, importing product data manually from a CSV or maybe JSON file should probably be the primary way to bulk add entries to the master table, but any automation possibilities for these would also be welcome.
Upon every new listing added, the values in these certain custom fields could also be automatically added to the master product table if not there already, after admin/moderator review (possible to correct typos etc) and approval.
Probably there should be settings for the admin to enable the feature only for certain categories, to configure which attributes would be included and which of them would be searchable upon adding a listing, as well as to temporarily disable the search possibility completely to only gather data to the table(s).
In practice, especially when listing the more popular items, the
sellers would rarely need to fill in all the basic details ever again, because someone else has already done that

I would love to use specifically Osclass for my project, but the option for the described workflow is what I'm after, so I might have to seek other solutions if you come into conclusion that Osclass won't be having this feature at least in the near future... I'm afraid I would then end up using that darn WP ecosystem, which is not designed for these things at all.