I'm not opposed to more than one site but the firm benefit of Amazon is free shipping without an order minimum and then having everything. Sometimes I need pet meds and I have to use all kinds of obscure sites for that stuff become Amazon doesn't have it or it requires a prescription that isn't in the budget.
I think what happened here is that I asked for an Amazon alternative and because no one could think of one they decided to make up things to complain about instead of admitting they didn't know of any alternative other than "don't buy things even if you need them or just drive 60 miles and pay more."