Well-if you think about it-having only one definition and belief in what a "car club" is -is as "simplistic" as it gets. I share your experience as to past car clubs. My best friend in H.S. owned a Triumph TR . He was constantly in contact with owners of similar Triumphs across the country. While they didn't hold official "meetings" they would occasionally meet at various events and go on "rides" together. They considered their group to be a car club.
Last I heard there was a "car club" in San Quentin the maximum security prison north of San Francisco who talk, discuss, and communicate, to the outside world about their "original" Mustangs. They consider themselves to be a "car club".
Bottom line-no one holds a monopoly on what a "car club" looks like.