Well, people could be incapable of going for one or the other as needed, even just "for a moment" -- which is the main issue.
Just it being "for a moment" doesn't preclude that moment to be very crucial to the resulting development.
This is true in principle. In practice, efforts towards accuracy are based on current beliefs, ideas and assumptions about the world. However creativity allows one to move beyond that, to explore if there exists some other local maximum higher that the current one. A better truth, so to speak. And without creativity you won't get there.
That is what I believe the author means when they say "somehow [the creative scientists'] early errors helped them find their way to the truth. They were...making many mistakes, mostly in the right direction."