It's the distance and the hills. Their choice of tower locations is not good for many NWA viewers. They're @ ~660kW and that's all their antenna setup can handle. So, no power increases are planned for KFTA.
BTW, KFSM is currently only at 550kW, not 1,000. They have applied to roughly double power to ~1,000kW ERP, but the project has been delayed until at least next year.
If you click the individual station's call letters on your TVFool results, you'll get a graph showing the number and relative size of hills between you & each station's tower. The TV transmitter tower is on the very far left and your house is on the very far right in the graph.
Reception strength is shown in spectrum colors, with white being the strongest and violet/pink being the weakest.