Well, honestly, title should read "40 million people downloaded the demo" by that standard.
If people aren't already reading it that way, I'd say they aren't seeing the full picture. I really get the sense (Hell, I know this is the case, even in the games media)| that people don't understand the business model for Mario Run.
It's a lot of downloads, and there's a worth to that for Nintendo's brand awareness and IP; hard to measure, but it means something. Beyond that though, the actual conversion to paying customers hasn't been touted a whole lot, and it's an open question as to whether or not people are putting money into this thing in anything that amounts to a meaningful way.