Goodness me, read one post and my jaw dropped.
Had a breakdown with psychotic episodes following my son's birth and was eventually diagnosed with PND, clinical depression and generalised anxiety disorder.
I was anything but weak, I survived a difficult childhood with abuse, alcoholism and domestic violence. I've been raped, physically assaulted and put into hospital, and bullied. I cope with arthritis and kidney problems, chronic pain and fatigue, being a single mum and was able to get through a pregnancy in a wheelchair with a toddler.
I am anything but weak; pregnancy and childbirth, then the ensuing sleep deprivation and emotional trauma are more than enough to take a very strong person and make them ill. Some families have a tendency to mental illness that is genetic, my own family has personality disorders/bipolar disorder running through it at all levels, distantly removed and remarkably similar.
Things may seem to become more prevalent, but that is not because most people are labelled wrongly, but because health care providers become more knowledgeable about and able to diagnose problems like this. Even if someone is just "a bit down" labelling them as weak isn't likely to help, depression runs on a (varying from individual to individual) spectrum and you belittling someone is only pushing them further down.
Tsk!