Earlier quoted context omitted.
I wouldn't say it has failed, but succeeded. The framing of the "marketplace of ideas" has really always been about paving over power dynamics and justify continuing harm by appealing to something external. In your marketplace of ideas, the hundreds of abstract individuals that are hararassers are equally as valid as one abstract individual just trying to live their life. It's working as intended.
It might be more accurate to say that the marketplace of ideas isn't all it's cracked up to be. It has failed to be the utopian dream some hoped it would.
These ideas weren't invented out of thin air, but to defend things that are hard to defend on their own merits. And just as the devinity of kings mysteriously only brought rights and no responsibilities, it is equally telling that the only time the "marketplace of ideas" is ever brought is in the context of why we shouldn't be doing anything about all of the hate speech.