That's a bit of a lie, actually. Education does work, it educates. But it doesn't work in the way many (middle class) activists think it does. Education doesn't stop people from discriminating against each other. In fact, it may well make people more proficient at discriminating.
The crucial question is what you're educating people in.
If you raise people's consciousness about, say, trans women, you're doing just that, and no more. You're not fighting oppression. Your consciousness-raising may have some effects to that end, but it's in no way guaranteed, nor is it certain in any way that your consciousness-raising isn't having the exact opposite effect of making the discrimination even more acute.
This is why: giving more information on trans women (I'm using our experiences as examples because I know those the best), our bodies, our hardships and lives in general makes us even more of a target. The more we are exposed to scrutiny, the more visible we are as trans, the better chances the oppressors have of spotting us as potential targets for discrimination, and there's just so much more surface area to attack, too. The mundane things you do with your body become available for public consumption - your relationships start taking all kinds of weird colourings in the minds of the majority. Majority starts seeing things that aren't there, but that doesn't stop the majority from seeing nonexistent things as real, such as the sex you were forcibly assigned at birth, or sexualities you would never know for your own. Educating people on what is doesn't necessarily change their cognitive frameworks in the least - it might reinforce the (false) frameworks instead. It's the old "don't confuse me with the facts" -thing that leads to "but you were a man, right?" -questions, and to endless headdesking on the part of the trans woman. As if it were so simple. As if the majority got sex and gender right in the first place.
Giving people more information about oppressed minorities also doesn't call the discrimination itself into question in any serious way. The focus is on the minority's deviance from the (unquestioned) norms of the majority, not on the prejudices and asshattery of the majority. Yet it's the behaviour of the majority that is the problem - the existence of the minority and its habits, phenotypes and stuff are incidental. Exposing the oppression borne by the minority may work as an appeal to pity, but it doesn't address the actual problem much at all.
The actual problem, of course, being discrimination and other reprehensible behaviour. Raising consciousness on that might help, but stopping oppression is not about the oppressed, it's about stopping the oppressors.