It is the same elephant. We are just describing different aspects.
It is a low Str high Dex converted into a high Physique character. Now it magically has inappropriately high Str and passes checks it should have failed, or it passes all Str checks because it never rolls any Str checks (see next quote), or it reinvents Str/Dex by applying ad-hoc penalties to restore the thematic. A catch-22 between those 3 options.
https://en.wikipedia.org/wiki/Vacuous_truth
If a character never rolls any Str checks, then they pass all their Str checks.
I would rather play the character than have them succeed. Part of the character are their flaws and weaknesses. The areas they are not as good. They will generally try things they are good at, but sometimes their weaknesses are challenged despite their efforts and intentions. (like if they tried to shoot the bull and the bull decided to introduce the waif to the road)
If you merge Str and Dex I can't play a low Str high Dex character. Either their Str never comes up (n/a Str high Dex), or when it comes up, it reveals the character is actually a high Str character (high Str high Dex).
PS: RE core strength:
Dexterity is already a large umbrella but core strength sounds like ave-mid Strength or ave Con to me depending on what you mean. Maybe that was a miscommunication between us. However it is irrelevant.