Multi-generational family cohabitation is nothing new and still the norm in many parts of the world. There's many advantages of it, though also carries risks (example is Italy's seniors exposure to COVID19).
The "jobless" part is more cross-cultural in its negative stigma, on the expectation that adults are contributing members of their respective societies. But as this article goes into detail, the quality of the job matters as much as having one. "Gainfully employed" > "employed", especially for the person in question.
I think another aspect of this is the age of the individual. When one is in their early 20s, then being "jobless" and "living with parents" is much more acceptable (both by the self and the society). But as one gets older, such as in the article's 40+ year old norm, then it becomes much harder. Add on top the Japanese/Asian emphasis on image and honor, then the resulting perceived sense of shame/failure can be very burdensome.