Metaphysical-ism (‘metaphysics’ with quote marks) is an ideology that seeks to totalize conceptual views resulting from inquiry into this area of philosophy. Metaphysics (conceptuality in terms of the rhetoric of classical metaphysics) is part of history and has a place in history, e.g., for development of conceptual competence (historicity of one's thinking) and for appreciating our historicality. We will always have conceptual issues about conceptuality as such. In that sense, every generation has its “metaphysical” issues of conceptuality, just as every life has its youth.
The translator of Heidegger's notes on “overcoming metaphysics” indicates the difference (The End of Philosophy, p. 84): It’s the difference between [A] “something... being... incorporated” (into a history of conceptuality that is growing/thinking beyond this history, yet as integral to how we came to where we are in going on) and [B] “something...being...defeated and left behind.” Heidegger works to defeat totalizing conceptualities: metaphysical-ism, while not negating metaphysics as part of Our history.
As Heidegger puts it (pp. 84-85, with modification by me—between ‘Being’ and ‘being’—and comment in brackets):
What does 'overcoming metaphysics' mean? In the thinking of the history of being, this rubric is used only as an aid for that thinking [of the history of Being, i.e., exalted conceptuality] to be comprehensible at all. In truth, this rubric is the occasion for a great deal of misunderstanding because it doesn't allow experience to reach the ground in virtue of which the history of Being first reveals its essence. This essence is the Appropriating in which Being itself is overcome. Above all, overcoming does not mean thrusting aside a discipline from the field of philosophical 'education'. 'Metaphysics' [in quote marks!—the so-called] is already thought as the destiny of the truth of beings, that is, of beingness, as a still hidden but distinctive Appropriating, namely the oblivion of being.”Then his notes continue in more analytical detail.
Totalizing a conception of beingness is the oblivion of being (e.g., transcendentalist displacement of the meaning of being), which is a species of Appropriating (but as self-concealingness).
The point, as merely introduced by Heidegger above, is paradoxical. I'm quoting from the beginning of that set of his translated notes, which is at the end of the book The End of Philosophy.
A related kind of point is that a child develops best in a setting that lets her / his ownmost comprehensibility have its way in learning to understand more fully (child-centered parenting, student-centered teaching), such that the reality that a parent / teacher shares conceals much from the child, for the sake of enabling her/his ownmost rate of development.
But Appropriating, for the 20th century, was forced into self-concealing oblivion of Our potential for growth beyond the history of Being, thus for enabling our incorporating of issues of being into a thinking that moves beyond that history which is nonetheless our history.
(Please don't equate my quick analogy with Heidegger's level of engagement.)
We don't try to defeat childhood by enabling growth beyond its horizon, but we would seek to dissolve childishness that totalizes simplistic views, as if growth is finished in adolescence—to dissolve childishness, but not the curiosity and love of learning which is innate. Inasmuch as understanding should outgrow stances, we should want to enable releasing potentials for outgrowing self-oblivion (e.g., strident presumptuousness), thus giving way for a re-leased childness (Inner Child) who moves on to better—higher, richer—horizons.
In a sense, a childishness of humanity made nearly the entire 20th century an inestimable tragedy.
