Aside from the typo, I'm not sure why it's hard to understand. Yes blacks freely choose to associate with other blacks, and yes gays with gays, men with men, men with women, blacks with whites etc. That's why I used the present perfect and not the present simple.
My point is that no one has chosen to be black, just as no one has chosen to be a woman, a man (leaving gender reassignment surgery aside for now), old, tall, or born in 2003.
Not all groupings of human beings are the same.
A: There are certain "groups" of people who belong to that group only by virtue of when, where, and to whom they were born. This includes black people, white people, men, women, tall people, bony people, ugly people, beautiful people, old people, young people, etc.; also one could say people with certain diseases or handicaps: people missing eyes, paraplegics, people with cancer, etc. It also includes all ethnic groups not organized along tribal lines.
B: There are certain groups that people belong to by virtue of political structure.This would include citizens of nations, residents of cities, etc. I'd also include here members of societies with traditional organization structure like kingdoms and tribes. And also religions with a clear hierarchical organization, like Catholicism, various Orthodox churches, Shi'a Islam, etc.
C: There are groups that people belong to by virtue of a belief in a common goal or common interest, like political parties, activist organizations, social clubs, hobby organizations, etc. I'd also include members of small religious bodies, like non-denominational churches and the like.
Group C can be freely entered and exited at any time, and by joining such groups, one usually recognizes the authority of the groups's leadership, who can speak on their behalf. If you don't like the leadership, you can quit. Free association. Group B is a bit more complicated, but by convention it is accepted that elected leaders can speak on behalf of their countries (both Bush and Obama spoke/speak on behalf of me, and much as I don't like it, they were/are still the leaders of my nation). While it's not as easy to leave such a group, and most of us don't choose to join them ourselves, we're still at least theoretically capable of leaving them. Even tribal and monarchial societies generally accept the leader as the head of their group, even if they didn't elect him.
But Group A? Who the hell has the authority to speak for blacks? By what authority? Who can speak for whites? For women? NONE of these groups share common goals, interests, or aspirations merely by virtue of their skin color, gender, physical condition, etc. What does Al Sharpton have in common with Clarence Thomas except that they are both black and both men? What does Nancy Pelosi have in common with Sarah Palin, and what do either of them have in common with Elizabeth II? And if blacks associate with other blacks, or whites with other whites, I'd damn well hope it's not *because* of their skin color.
This is why I cringe when I see groups like the NAACP speaking on behalf of black people, or worse, "leaders" like Jesse Jackson. Or the AARP speaking on behalf of the elderly. There are indeed black people who despise the NAACP and think it does more harm than good, and most of the elderly people I know want nothing to do with AARP. The NAACP has every right to speak on behalf of black people who agree with the NAACP (how's that for a tautology?), but for the "black community" in general? Please.
The NRA chairman can speak on behalf of NRA members, because membership in the organization includes recognizing the goals of the organization. The Pope can speak on behalf of Catholics because one of the definitions of being Catholic is accepting papal authority. But where does the authority to speak on behalf of women come from? Or on behalf of fat people?