We're told not to feed the wildlife at parks and beaches because of the dangers when they become dependent on visitors for their food source. It changes their natural behavior to the extent that it becomes difficult to revert to natural food sources in the absence of visitors.

(there are other behavioral and disease-related dangers but they're not as appropriate to this metaphor)

I think the more alarmed voices in this comment thread are not reacting to the change or "exponential progress" but are instead concerned about the impact of becoming reliant on something else to do our remembering.

This last part is anecdata (but no worse than the survey data in TFA), I think smartphone users have not really lost the ability to memorize, in general, but that the things being memorized are different. If the memory test (mentioned in a cousin-comment) had a set of 20 memes instead of 20 words, I expect most study participants would be a lot better at recall.

I suppose the question of "is this like junk food, though?" may be relevant.