Based on the author's figures and assuming complete independence of the conditions listed, only about 30% of the population would be untouched by any of them. At the other end of the spectrum, assuming complete dependence between the probabilities, the overall probability would be no higher than the highest among them, or 20%---meaning that 80% would be unafflicted. Assuming the truth lies somewhere between these two assumptions and splitting the difference, we'd get 55% unafflicted, which doesn't seem all that surprising. After all, no matter how strong our 'misery filter' may be, virtually all of us know someone who is clinically depressed, or an alcoholic, or who has dementia. We all know people who were sexually assaulted, although we may not know it. We know people in wheelchairs, and/or on disability. And these people are represented in our lives in numbers not far off from the proportion given as the rate in the general population.
It's a good reminder of the struggles that many face, often hidden from our daily view even if we are generally aware of them. But as a revelation of the power of our social filter, it seems exaggerated.