Why does SE believe that people don't like JPRGs?

[Sephiroth]

FFXIII Sales as of August 30th 2014 - 5.18 million units sold.
FFXIII-2 Sales as of August 30th 2014 - 2.59 million units sold
Lightning Returns Sales as of August 30th 2014 - 0.89 million units sold

Total - 8.66 Million Units sold as of August 30th 2014

Final Fantasy XIII sold 5,2 million + times for PlayStation 3 and 2 million + times for X Box. That makes almost 7,5 million times.

http://www.vgchartz.com/game/7727/final-fantasy-xiii/
http://www.vgchartz.com/game/24628/final-fantasy-xiii/

Final Fantasy XIII-2 sold 2,5 million + times on PlayStation 3 and about a bit over half a million times on X Box. That makes a bit over 3 million.

Together with Lightning Returns, lets say about one million, we have almost 12 million.

5.18 - 5.29 = 110,000 units difference
5.18 - 5.95 = 770,000 units difference

And 7 million is greater than 5 or 6 million so I am right (Final Fantasy X-2 has also been sold 6 million times if we count everything). I do not mean that in a provoking way, I just wanted to point it out so I have solved the XIII > X-2 or XII issue as well. Uncharted has sold 19 million, by the way.

No, I don't use FF Wiki or even Wikipedia as a source, ...

As much of a surprise as it is, Wikipedia is actually right. The mistake you have made is that you took the PS3 numbers as overall sales numbers. You probably did that purposely but an X Box Final Fantasy XIII is still Final Fantasy XIII and it should be counted except you really want to go the way of "consoles for which both game series came out" but that is not really fair, as it would make a great number of sales of Final Fantasy XIII insignificant and on which console it has been bought should not matter.

Source: http://www.vgchartz.com/gamedb/?name=Final+Fantasy+xiii

Here the overview: