I could not possibly disagree more with this. It's effectively saying that for 99% of human existence, we were all stressed and/or bored.
Stress is good for us, it promotes adaptation and resistance, but this can only happen when the stressor ends. The problem (as I see it) is that stress is increasingly a permanent fixture in our day to day lives right now, and we have less down time for the system to repair and adapt.
Of course there are benefits to modern life and I have no desire to go and live in a mud hut, but there has to be a better balance between what our bodies are designed to do, and what we're actually doing to them.