Yes, the point he was making was that Apple decides what it sells based on what it perceives is best for its product lines rather than sales figures.Macbook Air made ordinary Macbooks redundant, and thus the latter was discontinued.
The reason we don't have a 17" MBP is because the 15" rMBP has a better screen in all regards. The reason we don't have a 17" rMBP is because there isn't a card that can push that many pixels.
Therefore, Apple discontinued the 17" MBP. We don't know sale figures before it was cancelled but it wouldn't have mattered if it was a best seller--they would have discontinued it anyway just like they discontinued their all-time best selling MacBook when the product lines called for it.