That's interesting, thanks. Hypothetical legal discussions are always fun for armchair lawyers.
If there are other ways of achieving the same end result, that means that someone could use Amazon's method exactly, to the letter, but there would be no way of telling, based on the end result alone. So people are probably wondering why they bothered filing this patent.
You can't blame people for being suspicious. There have been enough bizarre legal judgements over time to cause anyone some worry. And there's always the very real threat of deep pocket lawsuits. Does it matter who is legally right if hiring a lawyer will break your bank account when the big boys sue you?
I am sure that people are also worried that there may be some obscure wording somewhere in there that will be interpreted in a not good way by someone some day. I know that's a lot of ifs, but still.