Men aren't "afforded" opportunities. They create such opportunities for themselves. They don't have to ask anyone else to give them these opportunities or organize it all for them. Women are free to do the same. Or they can just play in the top classes men have already organized and funded and whatnot and "afford" themselves of all those opportunities.

As for the math and science stuff, the problem isn't in making such general statements about gender. After all, it's almost certain that one or the other is actually going to be better at performing those tasks than the other, just as one gender is better at performing different kinds of tasks than the other.

The logic error comes in when one makes predictions about the potential "smarts" of any particular woman or man based on the general average capability of their gender as a whole, and thereby limits said individual's opportunities. Failure to recognize that any particular individual may indeed be far in advance of the average of their gender would be tragic.

I have no idea why the difference in those two things is so hard for some people to understand. To use a light-hearted example: just because a lifetime on the roads has told me that it's very likely that American women overall are worse at parallel parking than men, that doesn't mean that Mary is going to be a poor parallel parker: she may even be the best in the entire world at it - and yet that fact would still not change the fact that American women in general are worse at it than American men.