Why is it slacking off? Is it instead not normal for scientists to publish 3 papers over ~40 years? How do we know whether or not this is normal or abnormal? I

Why is it slacking off? Is it instead not normal for scientists to publish 3 papers over ~40 years? How do we know whether or not this is normal or abnormal? I'm inclined to believe we don't. And that we only assume so because of the incentive structures in place in our grant-first, publish-always system.