I'm not agreeing with the other guy and I get what you're saying, buy why would they think that? I highly doubt that Japan accounts for much more than 500,000 (it doesn't show up on any lists that I can find, so even this would be high balling it) of the 3,000,000 copies sold. It definitely didn't do a million since it isn't on the million seller lists, so over 2/3 came from outside Japan. Same with DmC. Sold sub 300K in Japan, the other 1.35 million came from outside Japan. In fact, DMC 4 sold 585,000 in it's first 3 weeks in the states.
There is quite literally no reason for them to believe the DMC brand has little equity outside of Japan. Sengoku Basara would be an example of that: it sells 250,000 to 500,000 in Japan yet sells next to nothing everywhere else, hence why no expansions or 4 in the west and why the latest anime hasn't been dubbed and only subbed.