This is done when they skip past direct recognition of racism committed against people of color and jump right into saying things like "well isn't X also racist?" (where "X" is some case of racism by persons of color and nearly always implied as a case of magically canceling out some instance of racism by "whites"). The end result in many cases is a successful attempt to keep things slippery, such that the plain fact of racist OPPRESSION -- which is racist action backed by institutional power -- is never plainly discussed. The diversion of blame games, Oppression Olympics (different genuinely oppressed/targeted groups trying to one-up each other in arguments over who is more oppressed), and placating the privileged (i.e. trying to make "white" people comfortable in discussions of racist oppression, trying to make men comfortable in discussions of sexist oppression, etc.) all end up being successfully used to AVOID rather than foster real discussion.
Witness its use in this thread, which has reached a few hundred posts in length but contains preview few posts honestly acknowledging even the most basic contextual issues (which are kinda important, given that they are what makes the difference between a "USA" chant being annoying but harmless vs. it being virulently racist/jingoist).