The simple fact is that women are not competitive with men. Not even close. If the best woman in the world were to join the men’s tour, I doubt she could crack the top 50.
Why? I don’t know. In 9-ball strength plays a part because the break is very important (although technique is more important here - Nick Varner has a very hard break, and he weighs 120 lbs). But it’s not just strength - it’s consistency, focus, and all those other intangibles.
In straight pool, which requires absolutely no strength whatsoever other than the ability to lift a cue, the highest recorded run for a female EVER is 89 balls. I know ten guys in my city who can run that many, and I’ve done it myself. In men’s straight pool competition (a race to 150 balls), it’s common for one person to run 150 balls without missing to win the match. The highest recorded run by a male is 562 balls.
Again, I don’t know why this is. But women are rarely competitive with men in physical activities. Even pure mental games like Chess have a wide gap between male and female abilities.
There is one exception: Aviation. Women have always held their own in the flying world. Women compete with men in the Aerobatic championships, and Patty Wagstaff has been world champion several times. Women had lower accident rates in WWII as ferry pilots, and the few female fighter squadrons in WWII (Russian) had excellent results (much better than the average for male squadrons).
I guess the point is that the differences between the sexes are much more complex than pure physical strength. We think differently, and excel at different things.