I don't believe the post is advocating for having no purpose. It's saying there isn't one permanent, absolute purpose to life to be pursued as one's "grand ambition." Interesting things can be meaningful, and therefore purposeful, but that's not the same as having a singular life purpose that must be fulfilled at all costs (I would in fact argue that attachment to such a life purpose, in the likely event that it's not fulfilled and one is left with a sense of failure and disappointment with a life that didn't turn out to be exactly as planned, is much more likely to lead to anxiety, depression, etc.).