I know this sounds pedantic but the author lists several studies pointing to social media impact, and still decided to go with that title and a big picture of Steve Jobs. If we forbid smartphones tomorrow and kept the rest of the Internet the same, I doubt anything would be much different at all.
Before smartphones, one would "surf the web" for an hour or so at night, and physically sit down at a PC. That's a radically different experience compared to the 24/7 always-on information overload and forever temptation of the smartphone.
The very article points this out: there was a time where the internet complemented physical life, in good ways even.
Second, smartphone engagement is shallow. On a PC one tends to read more, write more extensively, because it's easy to do so.
It's true that phones might be a better vector for it than most, but it's important to have clarity if we want to change anything. The article presents zero evidence for the damage phones cause without citing social media.