Roads have problems because they can crack and lead to dead ends. So you build better roads. The best kind of reputation systems will be the ones who carry a penalty for lying and misinformation.
If you lie that somebody has stolen from you, you shoot yourself in the foot, because now as people are less likely to believe you, you become the perfect target for a thief. So when a reputation system penalizes for false info, there's a very strong incentive against ever spreading it.
It's very hard to detect false info. Also info can be partially truthful or fully truthful and still be manufactured truth. Situations can be manufactured so that a person can report on something true even though the most important information is withheld which is that the situation is manufactured.
Example? Entrapment. A police informant could create crimes which ordinarily would never happen so that they can truthfully report on criminal activity. They might not be lying about the criminal activity but might not tell the jury that they encouraged or produced the circumstances for the activity.
So it's really hard to know what really happened. Lie detect tests are used to try to figure out if someone is telling the truth but even those can fail sometimes.
"Hard to detect false info" seems like maybe you're using the current paradigm and not really opening up to what a mature, decentralized rep system might offer. There's really no way to know how hard it would be, since we don't even know what it looks like let alone what tools and services will emerge to help sort it all out.
It's easier to defend something that's true than it is to defend something that's false. So over time as techniques improve and more energy gets put into it, I don't see why false information would have much chance.
Anyways, whether it's hard or easy to sort out false info you still want whatever rep system does the best job of it.
Judging people and people carrying reputation (and being regarded as honest or dishonest) is a part of life. How to do it (and whether it should be a centralized mechanism backed up by violence or a decentralized mechanism backed up by ostracism) is the question here.
To just challenge the usefulness of reputation.... I'm not sure what your point is. I'm sure you use reputation in your daily life, and I'm sure you wouldn't want a community where there's no way to differentiate the rapists from the heroes.