Imagine a guy who hates disabled people builds a hotel, so he bans all disabled people, and builds it in such a way as to specifically make access difficult for them. Years later, he sells the hotel to a new owner who has no problem with disabled people. So you have a hotel where the owner has no problem with the disabled, and neither do any staff...however due to the actions of the previous owner, the hotel is still built in such a way that it doesn't accommodate them (no disabled parking, no ramps, no extra considerations, etc.). So although the people currently running it are not actively discriminating, they are operating a system designed to discriminate, and need to fix it even if they aren't to blame for it.
It's the same with racism. The discriminatory practices of the past still have ramifications today, and even if we aren't to blame for them we must not fear them, not ignore them, not dismiss them, but recognize them and change them.