> Scientists aren't stupid. No one saw a paper where a predictor explained 1% of the variance in an outcome and based solely on a significant p value decided that was a great road to base an entire career on. The problem, as described by the parent comment, doesn't really exist in funding structures and the scientific literature.
Of course they're stupid. Everyone is stupid. That's why we have a "scientific method" and a formal discipline of logic to overcome fallacious reasoning and cognitive biases. If people weren't stupid we wouldn't need any of these disciplines to check our mistakes.
And yes, what you describe does happen all of the time. We literally just had a thread on HN about the failure of the amyloid hypothesis in Alzheimer's and the decades of work put wasted on it. Many researchers are still trying to push it as a legitimate therapeutic target despite every clinical trial to date failing spectacularly. As Planck said, science advances on funeral at a time.
Which isn't to say that small effect sizes aren't legitimate research targets either, but if you're after a a small effect size, the rigour should be scaled proportionally.