Yea you're right, I guess there is a distinction between reinventing and reimplementing. The authors even mentioned that concurrent mode is inspired by "double buffering" from graphics.
I am just trying to support the grandparent comment that the current optimization is at the wrong level of abstraction. React is at the level of a "scene graph" (dom). If it's slow, the first technique to reach for should be stuff like "occlusion culling".