Wouldn't call you naive or oblivious for holding this outlook - stoicism is widely under utilised by a lot of people. I differentiate between mental health and mental hygeine when I talk to people about these sorts of things.
Mental health is to do with things like personality disorders and problems with brain regulation. You cannot wish BPD away and it won't pass of it's own accord. The same is true with Schizophrenia and Anorexia and various other mental illnesses. Doctors and medical professionals can and do treat these people.
And then there is mental hygeine. If someone has a low mood, or they have anxiety or low level depressionn the questions they need to be asking should be around diet, exercise, thought patterns and their social life. Being anxious is a perfectly normal resposne in people who seek out anxiety inducing things - and the up and coming generation have made anxiety a feature of identity. It's become a comic talking point - as illustrated in the tweet you posted. It's a dangerous assumption for young people to make as poor mental hygeine (rather than health) can lead to poor and entirely preventable outcomes.
Great article. Very much enjoyed it. Keep up with the stoicism, it's a far more adaptive life pattern than despair. :o)