This enable/disable INTEGER turns on or off the hit-counting for this filter's paired Counter64, and per its description is also switched on automatically whenever the filter's event-log status is enabled. An admin cares because leaving counting disabled means the hit counter stays pinned at whatever value it last held, giving a false sense that a rule is unused. For example, when investigating a suspicious rule on VI 4 facing the Frame Relay uplink, an admin would explicitly set this to 'enable' before relying on the hit counter's value.