The ‘Thesis – Antithesis – Synthesis’ model seems to be another one of the ways Hegel is misunderstood. That model actually comes from Fichte (or perhaps Kant), and Hegel preferred other framings. Fichte is the one who fully denied the thing-in-itself and argued that the mind creates all things.

‘Idealism’ is a misleading term in this context, because it gets applied to nearly every view that’s a direct descendant of Berkeley (‘subjective’ flavor), Leibniz (‘objective’ flavor), or Kant (‘transcendental’ flavor). Hegel was more like Leibniz than like Fichte or Berkeley; in fact, the best comparison is probably to Aristotle.

Aristotle and Hegel would agree that there’s an objective world transcending our experience, one that’s in no way our creation; but they think that world must at its core structurally and constitutively resemble our minds, in order to be orderly and intelligible. (And, contra Plato, this order is immanent in the perceptible world, and the perceptible world is enlightening rather than delusive; so science / history can tell us about the world’s essential order, not just conceptual analysis / pure mathematics / divine revelation.)

It’s a bit like ‘we can understand ourselves, the world, and formal systems; so our selves and the world and our formalisms must be of one kind, which we can call “math”‘. Except at the time it wasn’t obvious that ‘math’ was any more universal or fundamental than, e.g., philosophy or chemistry or theology. So words like ‘form’ (μορφή) and ‘Spirit’ (Geist) were used instead of ‘math’ to gesture at the world’s intelligibility and its affinity with human thought.

Unfortunately, when you have a nontechnical quasi-monistic / pseudo-reductive insight like that, even a correct one, it increases the temptation to become overconfident in your intuitions, and in particular to endorse Mind Projection Fallacies. It’s perfectly possible for a true insight about the relation between mind and world to make you worse off epistemically in the end.