Amazon Seller Central is mind-blowingly bad from a user experience point of view. Why is that?

Originally I guess I figured it was just laziness and/or arrogance from Amazon but I’m not sure that makes sense.

I get that their primary focus is on the shopper user persona and not the seller persona, but I don’t think that can explain it. I also get that trying to build a consistent experience that works for the enormous range of product types must be a real challenge. But does their product data model need to include angstrom as a unit of product size measurement?

The only way it makes sense to me is that the process of selling on Amazon is made deliberately difficult to weed out sellers who aren’t serious about selling on there. Could that be it? Or is just laziness and/or arrogance from Amazon as I first thought?