How does the product profitability view work?

It runs the statement's own logic per product: revenue, discounts, returns, goods and the margin that survives them, so the catalogue can be ranked by what it keeps rather than by what it sold.

Products with no recorded cost are excluded from the margin ranking rather than shown at a perfect margin, and flagged instead. A product with missing costs would otherwise float to the top of the list, which is the opposite of useful.