I suppose the answer in general terms is that Ebay is like many other companies nowadays - they've done their research and are following whatever path provides them with the highest profits. I'm sure that research has shown them that negative feedbacks "hurt us all" and lower their income. There is no right or wrong - only profit.
Yeah, I think that is the bottom line, they want problems "resolved" without conflict and certainly no negative feedback, it lessens sales.
I sell a bit of stuff on ebay. I've been buying a lot of stuff, mostly tooling, at local auctions over the last couple of years to round out my shop and I wind up with a lot of surplus. I've also been helping a guy I know downsize his shop,so, what doesn't get passed along to folks I know locally, goes to ebay.
I've been burnt as a buyer in the past and I don't want to be that kind of seller, so I describe things very well, include really good pictures, and note any flaws I find. I've done really well keeping customers happy and have 100% positive feedback.
Recently I sold a South Bend 9b/9c change gear. I had described it completely, OD, tooth count, DP, bore size, and thickness, as well as noting what model it was parted from. I guess the guy who bought it did not know what model machine he has and when it didn't fit his mystery machine, he left some nasty feedback.
I called ebay customer service and they said to contact the buyer to try to resolve the issue. If the buyer would not agree to remove the negative feedback, they would as long as I made a reasonable effort. I contacted the guy, asking exactly what the problem was and what model lathe he had. He responded that the gear didn't fit and that was that. I contacted ebay a few days later and they removed the feedback.
Obviously, this situation is completely different from the OP's, he received junk, but I think it demonstrates ebays attitude. Their people do not have the skills nor the time to determine who is actually right,so they judge things based on a customer's history , willingness to resolve things, and willingness to jump through their hoops.