Because you can measure by harm caused, not just by thoughts thought. For example, I posit (without proof) that, because we have effectively banned hateful rac

Because you can measure by harm caused, not just by thoughts thought. For example, I posit (without proof) that, because we have effectively banned hateful racist speech in most standard professional workplaces, the people who work in those environments and used to suffer harm (through being forced to work in an openly hostile environment to them, through being denied advancement or equitable compensation, through the mental stress of being the target of hate speech, etc.), that those people suffer less harm today then they used to. - Is it perfect now? No. - Can people still be secretly denied promotions because of racism? Absolutely. - Does it happen less frequently in the aggregate than it used to 40-50 years ago? Almost certainly, though I base this claim on common sense for now (don't have scientific sources handy but I'm sure I can find some).