I think the KEY part of the email the guy got from Amazon is this:
"A careful review of your account indicates that you have required refunds on a large majority of your orders for a variety of reasons."
The important aspect is the word REFUNDS. He wasn't returning things and asking for *replacements*--he was asking for his money back. After a while a store or business begins to be suspicious about that sort of thing. It smacks of getting something, using it for a while, and then returning it because it is "defective" or "doesn't fit."
Basically, some people (I'm not saying this guy in particular) pull this to get the use of something for free. Some of the most notorious instances are women who get an outfit for a special occasion, wear it, and then return it & get their money back.