Hub-and-Spoke can centralize a schedule disruption at a hub (e.g., DEN for UAL) by re-routing to other hubs (ORD, IAH, etc.). The point-to-point model has a much harder time recovering from a mass disruption (e.g., aircraft going DEN - MDW - PHL - BOS is cancelled at DEN, which then dominos cancels the remainder of the points). The cancellations using point-to-point isn't normally a big deal until you have a massive weather system, fueling issues at DEN, now causing hundreds of cancellations and SWA's antiquated scheduling software that can't keep up the demand.