I kind of agree with this, but having recovered myself, I've found that addiction is more than just your drug of choice, it manifests itself in all sorts of little things. People find they quit drinking and then realize they've been compulsively shopping or eating. The same basic mechanism is the same and I think the author nails what it is: a cognitive-behavioral loop one has difficulty getting out of primarily because your brain is overvaluing the short-term over the long term for just long enough to engage in the cycle and strengthen the compulsion. Of course there's physical addiction, but not everyone likes that distinction. That is certainly powerful, but it's powerful to the extent that it makes the psychological addiction that much stronger, by having these very immediate responses with a clear behavioral solution (use your drug of choice).
There are people with really severe addictions, sure. In rehab there was no shortage of people who had to be monitored 24/7 and medicated because suddenly stopping their drug could actually kill them. There were others who were not as desperate. But I think it really is the same underlying phenomenon: substance abuse as well as gambling or some people who overeat or whatever else people typically need to go to rehab for - those addictions simply are greater and tend to have worse impact on a person's life. I was in rehab for alcohol having already quit every other drug at that point (causing my precariously balanced array of simultaneous addictions to cause one of them to dive head-first into the ground) and I wouldn't say that my addiction was the same as the heroin or cocaine addicts' problems. It simply was not in the same class, so I think there's already a recognition that everyone's addiction is different and unique to them.
Also, fuck, I'm clearly addicted to internet distraction. I'm writing this post instead of finishing my research paper.