Fredrik deBoer is spot on. In economic reductionism, again, deBoer denies the claim that socialists are typically economic reductionists with regard to race, that race is "just" an expression of class and that socialists believe that eliminating class would eliminate racism. deBoer is basically correct: he doesn't believe that, doesn't say say that, and most socialists who know what they're talking about don't say that. I won't say that nobody holds such naive reductionism — the internet is vast and full of stupid — but it's a fringe belief.
deBoer's makes his important points, and I have argued elsewhere that the liberation of black people, women, queer people, etc. within a capitalist system is to liberate only a fraction of those people: it is to ensure that black people, etc. are proportionally represented in the both the 0.1 percent of the actual ruling class, the 10 percent in the professional class (who serve the ruling class with privilege), and the 90 percent who are exploited and oppressed.
I want to make an additional point: the eradication of racism (and sexism, and all other forms of discrimination) requires power, especially regarding the material effects of discrimination. Black people will eradicate anti-black racism when they have the material power to do so. There is, of course, a moral dimension, but that moral dimension is useful only to the extent that it helps black people accumulate power. And in a capitalist economy power is money.
There are two ways for black people to gain money, and thus power. The first is for a few black people to break into the capitalist ruling class by becoming wealthy. No small few exceptional black people have done so, and (with the possible exception of Bill Cosby) good for them. I think they've done important work to fight racism.
However, if someone has power, it's very tempting for them to justify having that power, to believe their power is well-deserved. I don't think black people are angels. I don't think a black person with a million dollars wants to give up that power any more than a white person wants to. So, fundamentally, I think that rich black people are not going to be strongly motivated to address class issues.
Furthermore, the majority of black people will not be able to escape oppression unless they themselves have money. No matter how many black people are million- or billionaires, so long as a black person has to hold on to some shitty job under some racist asshole because they know that the only alternative is at worst starvation and at best some other shitty job under some other racist asshole, they won't escape racism. The only cure is to make sure that black people have good jobs paying good wages, with a good choice of jobs; then they have the material power to resist and overcome racism, not just in the workplace but in civil society.
A strike for black rights is effective only if the strikers have the direct and indirect economic power to survive it and actually use the strike to coerce the owners. A boycott for black rights is effective only if black people have enough purchasing power so that their boycott has a real effect. And it's stupid to argue — and nobody actually does — that only black workers should be privileged: to raise up the 90 percent of black people (and women, etc.) in the working class entails addressing class issues.