When I was in high school, my best 100m dash time as a senior was 1 second slower than the world record at the time. My best time as a senior was 1.7 seconds faster than my best time as a freshman. That last 1 second to get to world record level would have been exponentially harder than the 1.7 seconds I shaved off from freshman to senior years. Similarly comparing the difference between men's and women's world records to the distance between McKinnon and her nearest competitor is not meaningful. Gains diminish at the pointy end.