As a learning and growing graphic designer, it's very easy to sit behind a computer, focus on my screen, and do my own thing without talking to others. However, if I want to succeed in it as a career, it's very important to also see what others are doing and get feedback on my own work, which requires talking.
A better word is communication. What I do and what we do as graphic designers is relay information in the best possible way that is aesthetically appealing and functional. A great place to test out our ideas is with one another. We can learn from one another what works or doesn't work, and may even be inspired, encouraged, or challenged in our soluction. The importance of connecting to a community of designers is to sharpen one another's talent, which benefits the individual as well as the field.
AIGA is an example of designers coming together to discuss, display, and learn. The beauty of having a community of talented designers are the various perspectives and approaches each person brings. It is in a community that connections, friendships, and progress are made.