On Monday, September 4, 2017 at 2:31:04 PM UTC-4, dpb wrote:
I'd guess it's that they're all the same chair made in the same Chinese
factory just sold by different retailers and it's purely cost-driven of
cheapest source.

That possibility crossed my mind. But it still seems nonsensical. Even if it was made by one manufacturer, they must have been responding to some kind of impetus in order to expend the resources to modify the design so that it tilts upward. There doesn't seem to be a cost motive, nor does there seem to be a motive in terms of functional benefit. On the contrary, it's a functional negative.