That may be true, day to day, but we have had experts/appraise able before and will again.
We have at least a few that are value smart. I'm not among them, but I don't like you shutting the door. A lot of those with middling interest could help someone flailing with a piece of work, or at least suggest a site that could help.
I'm not against Barnebys, for it.
Plus, a lot of people who post on this thread just want to know what was the background history of an art work, or want help on what was it meaning, or the painter/author. Not all are seeking to have bought a piece at Goodwill and earn a zillion - some proportion of our posters are interested in the art. Sometimes that will, naturally, mix.