I often really enjoy socializing in person, but I can find it draining sometimes, versus energizing. I'm not sure how social I would be if my personal circle was larger at the moment. Many of my old friends developed throughout life have drifted away due to their marriages, relocations etc. Still, It's a valid guess.
When I was young people remarked on how I could spend hours, days, weeks etc. enthralled with my art, story-writing, or the library etc. I am not naturally "glib" either, and often think of the "perfect reply" too late to actually say it IRL. It's easier on the web, of course.