That was one of several definitions in that one section. With only that definition you're taking it a bit out of context but, it's important to note that we're talking primarily about systemic racism in the US which doesn't happen against white people as it's a system wide thing. It shouldn't be confused with general racism which happens against blacks, whites, asians, hispanic, middle easterners, etc. It's also important to note that systemic racism can happen against white people as was seen in the Ottoman Empire and is seen in parts of Africa and Japan currently.
This is one of the other descriptions from the same article. Right above the description you quoted:
Johnson defined systemic racism, also called structural racism or institutional racism, as "systems and structures that have procedures or processes that disadvantages African Americans."
Out of context even this quote would look odd as systemic racism against whites can happen in other countries as I pointed out above, but this is specific to the systemic racism in the US.
For more detailed definitions, here's a description and analysis from representatives of the Catholic Church in America:
http://www.usccb.org/issues-and-act.../racism/upload/racism-and-systemic-racism.pdf
Systemic Racism
Discrimination based on race and ethnicity takes many forms. The United States has made progress in eliminating some of the institutional, legalized racial discrimination of years past such as slavery, Jim Crow laws, “separate but equal” schools, and prohibitions on voting or owning land. These hard-fought victories deserve to be remembered and celebrated. Still, these advances are incomplete. Data on social and economic welfare show disparities between many persons of color and their white counterparts....
Or a civil liberties description that may shed more light on it.
http://www.aclrc.com/forms-of-racism
Systemic Racism includes the policies and practices entrenched in established institutions, which result in the exclusion or promotion of designated groups. It differs from overt discrimination in that no individual intent is necessary. (Toronto Mayor's Committee on Community and Race Relations. Race Relations: Myths and Facts)
It manifests itself in two ways:
- institutional racism: racial discrimination that derives from individuals carrying out the dictates of others who are prejudiced or of a prejudiced society
- structural racism: inequalities rooted in the system-wide operation of a society that excludes substantial numbers of members of particular groups from significant participation in major social institutions. (Henry & Tator, 2006, p. 352)