One stat to rule them all, or what if we merged Dex and Str?

[diplomancer]

We are not talking about Houdini. We are talking about my nimble waif making a physique check they should fail but you want to force them to pass.

The lumbering giant walking across a narrow ledge but falls off and has to catch themselves.
The nimble waif that is knocked down by a rampaging bull.

Our character's ability to fail at what they are not good at is as important as their ability to succeed at what they are good at.

And I'm talking about how, in most cases, you can describe it in a way that fits how you envision your character. Your nimble waif was knocked down by the raging bull (assuming what you're describing is a successfull hit from a Bull and then a successful str save against being knocked prone from the waif), but just jumped up from the floor immediately, because she's just that nimble, and has almost supernatural core strength. The result is the exact same as the hulk withstanding the bull with sheer strength,(I.e, they are both not prone) but the description is different.

By the way: one of the design goals of this change would be to give a relative buff to martials (because they have a greater incentive to pump either Str or Dex). Pointing out: "this makes a martial succeed in some situations he'd have failed otherwise" is the change working as intended.