So me, as an FBA seller has certain products that I've specifically added "DOES NOT FIT XXX YYY" and people buy it and then return it with the comment "DIDN'T WORK on my XXX YYY". I get enough of these stupid returns and Amazon suspends my listing, making my go through a contrition process telling them all the things I've done to remedy the excessive returns. I've got one very popular product, my best seller, that has gone through this 5 or 6 times in the last few years.
While I understand the perspective of fraudulent listings swapping in sub-standard products, the big improvement I am hoping for is that the warnings will actually get people to read the damn listing so they understand what the item isn't to be used for.