I don't think that's true. I've been working from home for 2-1/2 years, and I'm anything but an introvert. However, until March, I structured my life that I was meeting up with different groups 3-4 days a week after work. Running groups on Monday, Tuesday and Saturday usually (or skiing on Saturdays in winter), with occasional happy hour groups on Wednesdays or Thursdays, including the odd running group some Thursdays.
It is hard not seeing faces, but it's not too hard to do things like go get coffee before work, go out for lunch (or meet a friend for lunch), take a walk in the neighborhood. If you have a routine that puts you in front of people, it becomes easy.
I think the bigger challenge for many people is managing distractions at home. Piece of cake when I was single and living alone. Now that I'm living with my girlfriend and her kids, it's TOUGH to stay focused with a crying baby, home schooling, kids harassing the cats, etc.