I'm not sure if people are dumb enough to actually shell out money for such things
Yes there are a lot of dumb and uniformed buyers on ebay.
I see 13" classic MBPs from 2010 sell for 400-500 consistently. Or Macbook Air from 2008 or 2009 for $400.
Personally I don't have a problem with eBay. There are many good deals on computer parts and auto parts that I buy frequently.
Sometimes I have gotten lucky on Macs too. Last week bought an early 2014 Air with the i7/8/256 configuration for $750 and flipped it on CL for $900 in just two days.
I'm always looking for deals on Macs to flip them on CL. Hipsters in this area are always willing to pay a bit more.