Is "how" falling into disuse?

I’ve noticed an odd trend of headlines using “why” where “how” would’ve been appropriate, e.g., “Why This App Can Teach You any Language in Three Weeks.” While obviously an ad, this has been showing up in more reputable content. It’s been happening frequently enough I’m no longer sure it’s an unintentional error.

Has anyone else noticed this?

It doesn’t look like it:

[although this data stops at the year 2000]

I think so, even The New yorker today http://www.newyorker.com/magazine/2017/07/31/why-corrupt-bankers-avoid-jail. The article is about how.

I sometimes feel I want to scream at the number of ‘why’ queries on forums.

IMHO Google books was wonderful but it is obsolete when searching answer to questions that have a present time factor.

Without knowing whether this is actually a trend in headlines, I can see it being a psychological thing, like the obnoxious “one weird trick” or “you won’t believe” clickbait.
I guess the idea is that if you lead with “why” instead of “how”, you can trick the casual reader into accepting the assumption that a fact has been established, and they only need to know the “why”, not the “whether”.
Also, “how” could imply that the reader may have to pay attention to understand the topic or even follow some process to see a result, whereas “why” doesn’t imply any demand for attention or action on the reader’s part.

“WHY This App Can Teach You any Language in Three Weeks.”
Message: 1) This app CAN teach you any language in 3 weeks!
2) “WHY this app” = Here’s WHY you should buy it!
Vs.
“HOW This App Can Teach You any Language in Three Weeks.”
Message: 1) If you want to learn a language, there’s a process involved.
2) “HOW this app . . .” = Anyone interested in the technical details of how this thing works?