Well, sure, when it comes to just normal friendships, but I didn't think that's what we were talking about.That reminds me more of a introverted person. And their trouble isn't being focused on a single person but not possessing the skills to interact socially under all conditions..
Who ever focuses on a single person? To develop social skills, we have to talk to a variety of people. Having a single love interest doesn't prevent someone from communicate with many others.
There are also other problems. When a person's interests and passions are uncommon, finding many different people to share them with becomes very unlikely. For instance, I've shared with literally hundreds of people, most of whom have fled like frightened rabbits within the first half-hour of time we spent together.