I understand that the whole Madhyamaka conversation can be complicated and confusing, while the Buddha stuck to more plain principles. And I agree that the Buddha wasn’t demanding us to be PhD students in philosophy.
But as I pointed out, this is all present in DN 1, SN 12, and many other places in the canon. It’s not that we need to study Nāgārjuna. It’s that the Buddha is pointing us to something which Nāgārjuna tried to put into detailed philosophical arguments. I think the Buddha left it more for each individual to practice. He focused on all the wrong views and taught about practicing for right view. If we pretend the wrong views don’t exist, though, that would be a problem.
Like I said, while dismissing it as overcomplicated is understandable, we should remember not to throw out the message here. Annihilationism and eternalism are both rejected by the Buddha. The belief that somethingness turns into nothingness is annihilation. The idea that somethingness must always exist is eternalism. Partial eternalism, partial annihilationism, etc. are all rejected. You don’t need to trust the Buddha on this blindly. You can just contemplate if it make sense for nothing → something or something → nothing. Non-Buddhists realized this is a problem as well long ago.
“There are some ascetics and brahmins who are annihilationists. They assert the annihilation, eradication, and obliteration of an existing being on seven grounds.”
DN 1
“Vaccha, the wanderers of other religions regard form as self, self as having form, form in self, or self in form.”
SN 44.8
If ‘form’ is somethingness and becomes nothingness, it is the same as saying ‘form is self’ and the self is annihilated. Even if you think there are other selves which arise after each annihilated self, as some of the annihilationists at DN 1 believed. It is still an existing being → nothingness. I assume you accept the conservation laws which clearly show that matter (something) cannot turn into nothingness. But you reject this is true for the mind. But that would be substance dualism, and it would still assume the mind exists. So this may be some kind of partial annihilationism: matter is eternal (something → something forever), mind is annihilated (something → nothing).
If that is your view, I’m not trying to argue with you. I’m just trying to show you that the Buddha denied this kind of idea, and that other Buddhists have also shown that we can’t rely on it. This doesn’t mean there is something after parinibbāna. That is eternalism which is also clearly wrong. And it doesn’t deny basic Buddhism. It just means the Buddha’s teaching is deep and doesn’t fall back or rely on the dual notions of eternalism or annihilationism like most of the world. Trying to simplify it and fit it into one of these (‘either it’s eternal or it’s annihilated’) doesn’t help solve wrong views. It just perpetuates the two extremes which the Buddha claimed to avoid.