Instead of marching onward with perfect vision, science stumbles along behind leaders who occasionally take the wrong alley, after which it turns to other leaders who seem to know the way, then corrects itself again, until sufficient progress is made for the next generation to either thrust aside or build upon. In hindsight, the path taken may look straight, running from ignorance to profound insight, but only because our memory for dead ends is so much worse than that of a rat in the maze.
Not surprisingly, leaders are treated with ambivalence. With the exception of those who have come up with absolutely invaluable insights, such as Einstein and Darwin, leaders first inspire and stimulate, then guide and protect their followers, but usually end up stifling further progress. They become major obstacles: the dinosaurs of fields that they themselves helped create. Hence the ugly practices in which a number of upstarts revolt and get rid of old guru. They never do so literally, of course, but instead wield the academic version of the long knife, such as disparaging jokes during lectures, critical footnotes, bad book reviews, and after all is said and done, deadly silence.