It's weird to see this mashup of "sales don't matter" with HN's utterly lapdog approach to capitalism and free markets.
The argument here is that they are not strictly related to quality.
Are you gonna tell me the PT Cruiser, random example, was a quality vehicle because of its astronomical sales for years?
Not understanding why is popularity used as an argument for good sales. It's not. Tesla cars being well made (or not) is not a reason why they sell.