I think this post makes some interesting points, but anxiety is a slightly more complex subject. As a founder of a big company, there are ways it can go wrong, and being worried about those things is probably correct. A rational anxiety is not really an anxiety at all, but a fear. When the fear response is decoupled from threats in reality, that is when a response is considered anxious. Unlike in the case of the immune system, where more is better, with anxieties, the reverse is true. "Optimal human performance" exists at the point of accurate threat detection, for example if you were out hunting for your tribe and you heard something odd, it would be very useful for you to speak up, if would not be useful for you to suffer from a (non real) social anxiety, worry about making a fool of yourself and not say anything. The noise in the bush = potential real threat. The social anxiety = inaccurate mentalised threat.
Inaccurate mentalised threats are constructed in the brain for very good reason. Typically they are real when they form, and are required in order to stabilise the caregiving environment when young. (If mum/dad gets very angry when I make a fuss trying to get what I want, I quickly develop a fear of standing up for myself. This fear is useful to placate mum/dad, but not useful when I'm an adult and getting walked over.)
Strangely, the brain seems to have its own method to explain to the owner what these inaccurate mentalised threats are - dreams. And I can assure the author that the cure to nightmares is not as simple as recognising they are not real - there is a cure to them though. Dreams were extremely important to my own development/de-anxious-ing, so I wrote a paper on this function during my Msc in Psychology. It is free to download here: https://psyarxiv.com/k6trz, and was discussed on HN here: https://news.ycombinator.com/item?id=19143590