It is absolutely a market segmentation choice.

How do you know this?

It’s literally nothing more than a piece of firmware. WD is fairly aggressive about market segmentation, and firmware differences (or settings) are a big part of that.

You should read the rest of the thread. It's likely a completely different drive.

A completely different drive which lacks a feature in firmware. WD creates "completely different drives" which may have physical differences, but the firmware is also a huge differentiator in the market.