I think the real point of the whole teaching of 'impermanence' is because we humans invest far too much reality in the external world. That is especially so in modern scientific and secular culture. There is a strong belief in that culture that ''what really exists' is the universe as science reveals it and that the human mind is only an incidental or accidental feature of this vast ancient material universe. So in that context, people believe that what is real is what is 'mind-independent' - 'reality is what continues to exist when you stop believing in it'.
That is however a false consciousness, to the extent that the reality which we have invested in it, is itself the result of a mind-construction. But people have such firm conviction in the reality of that construction, that impermanence and emptiness of things are taught as a way to shake beings out of that conviction and to take responsibility for their existence. (It is interesting how because they believe that 'life exists because of chance', then nobody is really responsible for how things are.)
From the
Berzin page referenced above:
According to the Chittamatra (Mind-Only) school, the only way the existence or nonexistence of anything can be established is exclusively in terms of its relation to mind (sems). Mind, in Buddhism, refers to the mental activity of merely giving rise (shar-ba) to a cognitive object and, simultaneously, cognitively engaging (‘jug-pa) with it; and not to the instrument that does the cognizing. The former aspect of this activity is called “clarity” (gsal) and the latter “awareness” (rig). “Merely” (tsam) refers to the fact that this activity occurs without there being an independently existing, separate “me” that is actively making this activity happen, or passively observing it. ...
Mind-only, or “aspect-of-mind only” (rnam-par rig-pa tsam, Skt: prajnapti), then, does not mean that everything is a way of being aware of something (shes-pa), or that everything exists only in our minds and that no other beings actually exist. If that were the case, compassion for others would be pointless. Mind-only is not a solipsistic view of reality.
Whereas, modern culture has invested the 'external world' with a reality which it is convinced exists entirely independently of mind, and then tries to explain mind as something which is a product of that external reality! This is a confused state of being.