Its actually right in the posted link:

The “Sold by Amazon” program resulted in prices for some products increasing when Amazon programmed its pricing algorithm to match the prices that certain external retailers offer to online consumers.

As a result, when prices increased, some sellers experienced a marked decline in the sales and resulting profits from products enrolled in the program. Faced with price increases, online customers sometimes opted to buy Amazon’s own branded products — particularly its private label products. This resulted in Amazon maximizing its own profits regardless of whether consumers paid a higher price for sales of products enrolled in the “Sold by Amazon” program or settled for buying the same or similar product offered through Amazon.

Amazon is actually fixing the price that you are selling on Amazon matched to what other sites are selling. There's no point in leaving if you're selling your widget on other platforms for the same price.

The article says so.