I never said people can take time off at whim! They (quite rightly) can't!I've taken time off work for depression. Work was contributing to my condition. I and my family are very glad I did because if I hadn't there is no guarantee that I would be here now.
Not sure if in your eyes that makes me a snowflake as your posts suggest but thankfully that attitude is out of step with with current thinking around mental health.
I guess to answer your question, if work is adding to clinical depression then yes everybody experiencing this should be able to take time off.
I guess the thrust of your post is that people can take time off on whim, but of course it requires a visit to the doctors and a diagnosis of a serious condition.
I would suggest the midlife crisis jibe is a poor attempt to undermine the severity and seriousness of the depression you mentioned in the previous sentence and it does you a disservice.
The symptoms described, however, are exactly what thousands of people feel simply because of the pressures of their job - but there's mortgages to be paid, kids to be fed, so you go back into work, week after week after week after bloody miserable week! I did! Yes, for sick leave (above a week, I think?) you need a doctor's certificate - even with these though, your sick leave can lead to a disciplinary hearing and ultimately dismissal on the grounds of inefficiency due to ill health. It happens all the time, in the Civil Service for example