Maybe because it's less terrible. Some time I had a very surprising experience: I was shopping for a book and found it at bookdepository.com. It was nice experience: predictable price with no marketplace sellers or exchange rate shenanigans, shipping costs visible up front, and cheaper than Amazon. The surprise? Amazon owns it.
It is always nice to drop links to something other than the local monopolist that pops up on the top of search results. Like the original publisher, Wikipedia, or default to a search on bookshop.org
