One of the main aspect of Data Science is... Science.

I know some people who I would qualify as scientist without a PhD, but they are extremely rare. On the other hand, I've seen countless unqualified people apply and get (lousy) data science job because the "title" itself is very vague. I'd be more inclined to hire a PhD (who's been through a fairly painful scientific training) in, say, material science, then train her to data/programming, than get a good programmer and train her for science.

I'm not for a "Data Scientist Association"[0], but I'm not for diluting the value of all the effort I made to effectively become a data expert AND a trained scientist.

[0]Rant: there is a world outside America.