Well, again, you don't need to prosecute to get your stolen stuff back. Prosecution is irrelevant. I've gotten stolen items back after 20 years, but nobody was prosecuted because the statute of limitations was long expired and the person who possessed it at the time didn't know it was stolen. Unfortunate for them, but life isn't always fair.
and was your stuff cameras and lenses? Or something else? Had you filed a police report all those many years ago? And when you filed the police report, did you have to show evidence that you actually were the owner of the stuff in question (I'm specifically thinking of original receipts with dates and serial numbers etc).
My point is that the police aren't going to just come to my house and collect up my belongings based upon some photo that I posted of my belongings on the internet. There's much more involved - prior police reports, evidence of an actual crime, maybe even an insurance claim? and the perpetrator of this imagined easy scam / fraud better have a pretty good idea about when I bought the stuff and hope that I don't have proof that of that.
EDIT: (added later) and after some thought I see your point too. I think what you're saying is that If I bought a 50 year old lens 5 years ago and advertise it for sale today, with photos showing the serial number and that lens was reported stolen 20 years ago, and the person from whom it was stolens sees my photos and realizes that it is the same lens, then all he has to do is report this to the police and...somehow the police come knocking on my door (possibly in another state though? How would that work?) and re-posses the lens that was reported stolen 20 years ago...yes?