You probably belong to several. And they're important to you. Without them we would each be alone and adrift in a fragmented and tumultuous world. Therefore, building communities seems important to me. Understanding communities is important.
Communities have subtle dynamics.
In a large community, smaller groups tend to form, usually groups with an intense common interest, such as computer programmers, or old-time musicians, or cloggers, or vegetarians, or chiropractors. This is natural. These sub-groups are beneficial to their members, who form stronger friendships with people with whom they share an intense common interest, and beneficial to the larger group, which gains in vitality and love because of the strengthened friendships which have developed. Unless the sub-group becomes a clique. Cliques are inward-turned groups.