A politician that bans or regulates sugar is not going to be popular. People want their sweets, or at least the option to have sweets. So what is the medical system to do if it can’t modify the food environment? It generates drugs that treat the diseases caused by the food environment. Similar with mental health.
There are society-wide environmental factors likely contributing to huge rates of depression and anxiety, but how is any one person or organization supposed to change that? So what does the medical system do? It generates drugs to treat the mental health conditions caused by environmental factors.
It’s a bad equilibrium but it’s hard to see a path out. Otherwise if you decide drugs are bad you have still have the environmental causes there and a bunch of untreated diabetes and suicidal people.