that in order to participate in discrimination, one has to actively and with malice aforethought choose to discriminate — in order to be sexist, one has to be a sexist, in other words (or to be racist, one has to be a racist; in order to be homophobic, one has to be a homophobe, etc).
And, well. No. In fact, you don’t actively have to go out of your way to discriminate in order to participate in discrimination — that’s kind of the point. Some of that is already built into the system that everyone is part of. You get it, positively and/or negatively, no matter what; everyone does. You may then also decide to support discrimination in one way or another, and that’s the thing that changes you from being (for example) sexist to being a sexist. But to deny that baseline discrimination we all deal with because you’re not by your own lights actively trying to promote that discrimination is silly. It’s there, it’s real and it’s measurable, and you take part in it, one way or another.
This is the difference between institutional racism and personal racism that people tried to teach me some time ago and I knew then I didn't understand yet. An individual can hate black people and actively yell at them or otherwise try to make their lives worse. But our entire community works together to put together a police and judicial system that systematically is biased against black men at every decision point.