In building, some guys are really skillful at getting the foundation and framework of a building done. They are often not very good at the finish work, like flooring, cabinetry, and painting. Other guys do the finish work. Both skill sets are absolutely essential to producing a quality building. Both kinds of mindsets are required. Neither is more important than the other.
In baseball, some pitchers are great at starting the game, picking off batters, throwing pitches that keep the ball "in the park" and base runners off the bases. Other pitchers are great at finishing, throwing 100-mile-per-hour fastballs that one can barely see, much less hit. However, they couldn't (with rare exceptions) do that for seven or eight or nine innings. Both kinds of skills are necessary to win baseball games, and both kinds of mindsets are necessary for success. Neither is more important than the other.
Pick your profession, pick your endeavor. The same sort of starters-finishers dichotomy exists.
To be sure, there are other "roles" and other "role players" that fit somewhere along the continuum between starters and finishers. The point, however, is this: we need each kind of "player" on a successful team. They all bring something unique and important to the task.
And, of course, none is more important than any of the others.