I intensely dislike the cynicism of this and other similar statements.
It's a truism of American culture that any group of people is somehow stupider, meaner, and more hurtful than any of its individual members. Yet our lived daily experience is that often our most rewarding, beneficial, and joyful experiences come when being a member of a group.
I mean, we are a group right here and right now in this thread and I assume everyone participating still feels it is a net positive for them to do so. The idea that all groups become bureaucracies, mobs, or totalitarian regimes is this weird extreme perversion of American values. Call it toxic individuality.
I think a value-free and more accurate observation is that emergent properties exist: a group can have observed properties that are counter to the intentions of any of its individual members. The aggregation process itself can be dynamic, iterative, and complex in ways that break a simple coupling between invidual intent and total outcome.
This can be bad, when otherwise sane reasonable people get riled up in a mob. Or it can be good, when a choir's tone sounds more in key than any of its individual singers. It's highly dependent on both the individual members and the communication structure of the group.