SPS Tools says that "because one supremacists (sic) went postal, all supremacists are responsible." Yes, just like all Nazis were responsible for the atrocities committed by any of the other Nazis.
"Is that like when a small group of Muslims took down the World Trade Center, ALL of Islam is guilty?" No. But when Al-Qaeda Muslims took down the World Trade Center, ALL Al-Qaeda Muslims were guilty.
"Or because of Hitler, all Germans should be exterminated?" Nope, just all the Nazis ... and those that got caught were exterminated or imprisoned.
That's not a root cause of racism ... that's laying blame where it belongs.
Best,
RTD