It is interesting, though negative social and environmental factors can contribute to mental illness. The article makes a good point that sometimes normal reactions to a situation get labeled as mental illness symptoms so people that aren't actually mentally ill might be seen that way or become convinced something is wrong with them. However at the same time disregarding someones mental illness symptoms as a 'normal' reaction can also be harmful.

For instance sure a lot of how I felt after trauma that led to my PTSD was a normal reaction, however the fact that I still have terrible symptoms that have gotten worse is not a normal human reaction it is a mental illness brought on by situational causes, and as far as I know like with other disorders one can be more per-disposed to a certain mental illness due to genetics or whatever.