[DubiousPusher]

It may be based on testimony but this does not mean there is no metric for quality. There are tools which can help hint to us about the quality of some information: double blind controlled trials, reproduction, systemic reviews, longitudinal studies, published pre-study methodology, multiple lines of evidence. And some are considered as better than others. For example, a double blind controlled experiment is considered more indicitive of causal effect than an observational study. Which is still better than a self reported survey.

I don't think it's entirely a bad idea. It would be hard because it would be an elitist endeavor. As in, criteria and protocol would have to be established by a small group ahead of time rather than democratically. Such institutions are vulnerable to capture or stagnation. But they can be really useful while they are true to their mission.