I would consider myself part of the left and I wouldn't necessarily dispute this. Blanket statements are fun.
*Edit* - Okay, now that I've read the whole article I can actually comment on the rest of it:
I think it's just as disingenuous to say that "Democrats intentionally promote the idea of racist America to get black votes" as it is to say "Republicans are racists." I'm sure there are some Democrats who think that way, just like there are some Republicans who are racist. Also, to say American is the least racist country in the world (whether true or not) is entirely different from saying it's not racist. There is plenty of institutionalized racism in the US. For instance, black and latino defendants are more likely to be convicted, and when convicted in general receive a harsher sentence, than similarly situated white defendants.
Is it better than a lot of people act like? Hell yes it is. But that doesn't mean it's not a problem at all.