(I feel like the author doesn't say enough to distinguish the personality differences between the example lives and the new "single" life.)

I'm all for reducing complexity in one's life but not at the cost of surrounding myself with people that challenge my own understanding and beliefs. They're not there to convince me to change my mind, instead they help me solidify my position better. Having different parts of one's personality is important to not become a narrow-minded or uninformed individual. Your own personality facets shouldn't be so divergent that you change so much in different social situations and never move beyond superficial communication.

If I only ever focused on one facet of my personality I wouldn't learn anything. That seems counter to the approach an entrepreneur/founder would need to be successful.