My understanding is that Amazon continues it for 2 reasons: it's similar priced, but more importantly they can get the doors at massive scale and they're the same. Styles, colors, materials with desks change over time. They have to source sometimes ~10k desktops in a quarter with little lead time. You can't do this with desks but you can with doors.

Or this is why they told us we wouldn't get white desks in Seattle when we had em in sfo. Even though we got the same legs.