I compltely agree and think you have brought up a crucial point both to this discussion as well as in a broader context.To be politically correct despite the fact that scientists earn 'PH.D's, replace 'why' with 'how'.

Temper this with the fact that all definitions (theories, conjectures, etc.) are defined in terms of other definitions, which results in circular reasoning, or accepting some definitions without proof.

Isn't the linked example you gave sufficient?

All rational axiomatic logical strucures are inherently tautological. This applies to physics as well as formal mathematical structures.

But there is a significant difference between the two which seems to be often forgotten.

. In mathematics a valodly derived theorem consistent with the structure cannot be untrue. Axioms cannot be untrue.

Regarding the logical structure of physics , history has amply demonstrated that neither one is neccessarily valid as applied to the real world. Particularly recent history i.e. SR GR QM and the established threoms and logic they either falsified or limited.

Only a fool would fail to recognize that, not only are these systems the only way we can possibly understand and describe the world , but that the incredible power and utility of these structures renders insignificant any small glitches or required amendments.

At the same time it might be prudent to remember that history is relative and we are living it right now. That the future may reveal that a dogmatic certainty in the theorems a la mode may be as defensive and shortsighted as Ptolemists resorting to epicycles rather than examining the real questions they were confronted with. IMHO!!!!!