Short answer, because there is nothing to underpin modern discourse.
One-step reasoning is scaffolding cantilevered over an abyss of nihilism: so there is no incentive to point out this fact.
By one-step reasoning I mean that a question posed in modern discourse carries the expectation that it be answered in its own terms, briefly (preferably in a single sentence), conclusively, and without reference to any other mode of discourse.
To question the discourse is to demolish it. Therefore:
It is not permitted to re-frame the question as ill-formed or prejudiced;
It is not permitted to refer to transcendental values ('the good' or evil; truth, beauty or virtue).
Hence the shallowness, rhetorical trickery, emotional manipulation of all modern public discourse.
Hence we simply get several or many incommensurable answers to any particular question from the discourses of politics, law, economics, the media, education, science, 'ethics', religion...
Which discourse prevails in a specific instance is simply a matter of which one is successfully imposed.
And there is no possibility of principled compromise, because there is no underpinning value (whether general or specific) which might be optimized by a compromise.
So, instead of compromise, we get horse-trading, deal-cutting, carve-ups and trade-offs.
But nothing can be done about it. Everyone is as bad as everyone else: and purportedly 'in-depth' analysis is merely distally incoherent at the third-step of reasoning, instead of at the proximate second-step.
We have now arrived at Ralph Waldo Emerson's desired state when he asks: "Let us having nothing now which is not its own evidence"
- that is to say, self-evident within an already-established mode of discourse.
No more to be said: nothing to say.