There is an easy way around all this.
If people want to know what they got, they should post a thread asking for identification of the part. Where to find casting numbers, application, rarity, whatever.
Armed with that info, most people can do some searching on google or ebay or whatever and find some history.
Value doesn't have to be any part of it. Information makes it possible to find value on your own.
Otherwise, and there are other threads about this, flippers AHOY! As soon as someone has a WIW thread you can just almost hear the flippers licking their lips.
A thread about identifying a part is not against forum rules and gives the asker all the info they need to find their own value. If there is something truly scarce, and hard to research a value on, there are two mindsets anyway: It's super scarce so it is worth a bundle, It's super scarce but no one is actually out there looking for one because of that so it is worthless. And besides that, no one here would know a proper "appraisal" for an item like that anyway.
Honestly when I see a WIW thread lately, I am of both minds- I get excited to see what someone has, because there is usually pictures, and cringe at the same time because I can see the vultures circling and hear them licking their chops and yelling down the hall "Betty! Go gas up the truck we got a live one!"
So I am fine with status quo on the topic. The flipper sceeze outweighs the curiosity I have about random parts or cars.