It's a key point we need to grasp to make sense of evolution.
Another equally common fallacy is essentialism or what Ernst Mayer called "The dead hand of Plato".
To Plato everything we experience is nothing more than shadows on the cave wall - imperfect copies an unseen, ideal reality. In Plato's world of "essentialism" all the shapes you could ever draw were mere representations of “essential” shapes; the essential triangle really did have angles adding up to precisely 180 degrees, parallel lines of the “essential” rhombus really did extend for infinity without merging.
According to Mayr biology has suffered from its own version of essentialism in which tapirs and rabbits are treated as though they were triangles or dodecahedrons. It is as if there was a perfect essential Platonic rabbit hanging somewhere in conceptual space along with all the perfect forms of geometry. Variation among real rabbits is seen as a departure from the correct form of the essential rabbit to which all bunnies are tethered by invisible elastic.
It is this error that leads to silly questions about so-called missing links and pointless arguments about species, genera and taxonomy.