You answered your own question. "Very flexible" is a plus for Amazon because they can cover everybody's use-cases with a single concept. "Very flexible" is a mi

You answered your own question. "Very flexible" is a plus for Amazon because they can cover everybody's use-cases with a single concept. "Very flexible" is a minus for end users because they only need to take care of their own use-case. So you can say it's a "natural" complication, and you'd be right, but that says nothing about usability, which is where "issues" tends to come in.