No doubt the effort to solve problems and improve one's self and circumstances have been powerful forces behind progress. But arguably, a focus on optimization and perfection can be forces that prevent the kind of progress you praise.
Similarly, I feel comfortable treating a drive towards improvement the same I do a drive towards perfection, since without an end goal (perfection), you can't have improvement, since you cannot say if what you're doing is bringing you closer or farther from 'good'.
I do agree with you though that an individual can focus on hyper optimizing their personal life to the point where it is not good from a societal perspective; however, that's is not what I gathered the article was arguing ("Enough of our mania to be the best and the most, he says. It’s time to content ourselves with being average.")
Optimiziation may be a subset of problem solving, but surely you'd agree that a problem can be solved even without the situation being brought to optimality?