First let me start out saying that everything I've written below is what *I Think*.
I think it's doable, never did like any naysayers I ever worked with. Although, I think you would have to get it right the first time around which may be a little more complex than you think at this stage of the game.
There are social media hurdles and issues out there like hackers, spam, etc... that may also hinder your progress and efforts if not mapped out, addressed and metrics properly from the beginning.
Your initial efforts and strategies may include data base access with references to a subset of software recognizable images with descriptions and definitions that are commonly looked up to display to a user and asking the user if this is what they are looking for before posting to a social media users group for that given topic.
You may have to run your own network database servers (I call them scrapers) like the big search engines do to update your databases with images and image definitions for specific topic databases (I have no idea of the legality of all this and I don't understand how other big companies can get away with it).
Your software may also include random generated text/words/numbers verification for a poster to enter before submitting to a particular feed or group to battle off the spammers and hackers so these false postings don't go to the specific topic group.
Now there is already a lot of image recognition software out there available in apps but what you're tying together is a user group or social media group aspect to it (the image part of it) in a by topic level it sounds like. It's doable and it can work if filtered, managed and resourced correctly I think.
And yes, in a way all this is already being done without a front end app like it's done on this site and thousands of others. I say go for it, it can work if carefully crafted and managed. Of course there are many other facets to this which I haven't even mentioned or given much thought to at the moment.
Now the question comes would I use it? I might use it if it worked at the image definition level then if I needed to pursue the image level further be given an option to forward the images and question to a users/social media group for that topic.
There are some issues here though, when you're dealing with a general topic like antiques (there's a lot of things out there!) it would be so vast your resources for a local in house image database may be limited locally. And of course there would be a lot of topic levels that would have to be grouped or sorted out.
Can it be used for other things other than antiques? Of course, I think there are already apps out there for a lot of images such as trees, flowers, vegetables, etc... Then you could expand the image recognition software aspect of the app to a specific user/social media group.
You could even create new software for other web forums for certain topics to embed into there own app or web site to allow some of these topic questions to come into there web site into a certain area of it to help create new members for there own site! The possibilities are endless I'm sure. I'm a sayer, not a naysayer, anything is doable!
Good Luck!
Kevin