When you work alone, you need to socialize at some level.
My books are primarily plot driven but the best plot in the world is useless if you don't populate them with characters that readers can care about.
In suspense novels even subplots about relationships have to have conflict.
In other words, the people who populate my books are more than caricatures.
Sometimes you can't be what you ought to be, you can't have what you ought to have.
Of course, all writers draw upon their personal experiences in describing day-to-day life and human relationships, but I tend to keep my own experiences largely separate from my stories.