It's the term itself. You can differentiate between Racism and racism, but as soon as you call someone a racist, you've labeled them as an evil bigot. Racism is bigotry, but bigotry exists in tons of forms. It's hard to recount the absurd, prejudiced attitudes even intelligent and moral people will have about things like nationality, religion, programming languages...etc.
Well, I don't know. The thing I do, and it feels like water dripping on stone, is I call out small assumptions whenever I see them, and I always, always draw attention to communities of color as being people, citizens, deserving of all equal opportunities (and pointing out how some law, algorithm, or assumption is denying them one).
It's a real gentle advocacy, but it's also easy to stick to because it's absolutely the right thing to do once you see how stacked against CoC the system is
There's nothing wrong with this, in fact it is probably the correct thing to do, but you can really quickly become that guy. Oh, there's Johnny again, acting like we're all a bunch of racists and we don't understand the daily struggles people have. You can get tuned out really quick, if it's presented in terms that compare one group to another, the implicit assumption that because you're not in that group, you've had it easy. When people feel confronted in that way and they know they haven't had it easy, they're less likely to care whether they are racist. That's the impression I get from the groundswell of support for someone like Trump. The small-racists aren't supporting him because they hate other people, they supporting him because he act like he cares about them and at least rhetorically will stand up for them.
I guess what I'm saying is, it's important not to lose sight of the fact that the goal must be to stand up for all groups of people and to deny bigotry in all of its forms.