My issue is that they should clearly state if its Pt to Pt or if its based on actual miles flown. Simply saying that its complicated and a nightmare to track is not a good reason as why it should this metric is not used. I am almost certain that the metric of actual miles flown is captured on each and every flight. The question is if the airline is using pt to pt they should clarify it clearly in the T&C. The current T&C below does not clearly state if it is based on distance travelled or distance measured.
On nonstop and direct flights, mileage credited will be calculated based upon the distance from origin to final destination, regardless of the number of stops.