I'm getting bored with this back and forth because your arguments hold little water.  But one final perspective:

"It is difficult to win an Olympic medal at age forty if you gave up sports when you started your career. This IS true.".  Just because you said it does not make it true.  If woman are truly at their physical peak at age 40, I would suggest that there would be many many age 40 athletes competing.  There are not.  And the most likely reason is that woman DO NOT physically peak at age 40.

More athletes does not equal better.  Plenty of examples of star professionals failing in one sport only to excel in another.  Drew Brees quit tennis as a competitive junior (lost to Andy Roddick).  Does that mean tennis has better athletes than football?

No CANADIAN swimmer won 4 medals in one Summer Olympics until Penny O.  So what is your point?  Easier to win swimming medals? Right.

Comparison is wrong.  It is not Pro vs. amateur it is age related.  Older amateur similar to older pro.