In my opinion, the Sutta Pitaka and Mahayana Agamas (the Mahayana equivalent of the Pali suttas) discuss the nature of the self (anatta, empty of self, dependent arising) in such a way that it is useful to the path towards liberation from suffering (such as overcoming self-view or sakkāya-diṭṭhi).
Meanwhile, the Sutta Pitaka and Mahayana Agamas (the Mahayana equivalent of the Pali suttas) do not discuss the nature of other non-sentient things (e.g. a chair, the universe, atoms, five aggregates), beyond noting that other things are conditioned (sankhara) and impermanent (anicca).
On the other hand, Nagarjuna's Madhyamaka seems to have expanded on these concepts to cover the nature of all reality (empty of inherent nature / svabhava, dependent arising, dependent designation). On top of this, Madhyamaka also posits that emptiness itself is empty of inherent nature.
To a non-Mādhyamika practitioner, Madhyamaka's discussion on the nature of all reality may appear to be an exposition on the "poisoned arrow". That is to say, it is not useful to the path towards liberation from suffering. Some might even say that the nature of all reality falls under the fourth imponderable (Acintita Sutta).
From a Mādhyamika practitioner's perspective, how is Madhyamaka useful to the path towards liberation from suffering? How is it useful to personal practice?
This should not be seen as negative criticism towards Madhyamaka. Rather, I seek to understand its usefulness to personal practice.