Most LISPs don't give you the most power. They are usually GC'd, and usually don't have access to directly modify memory, like you can with anything in the realm of C.
The foot-gun the give you is expressiveness, which allows you to make code unintelligible, rather than power to do anything that you feel like. (I'm not aware of any surviving LISP that would allow you to modify the structure of how cons cells are generated, for example).
There's certainly power in expressiveness, but it isn't the godlike power of C, where you can potentially damage hardware.
That, I think, is why we don't have a "Rule of most power".
Most actual Lisp systems can access random memory and define C-like memory structures. Otherwise they would not be able to integrate with other software.
The foot-gun the give you is expressiveness, which allows you to make code unintelligible, rather than power to do anything that you feel like. (I'm not aware of any surviving LISP that would allow you to modify the structure of how cons cells are generated, for example).
There's certainly power in expressiveness, but it isn't the godlike power of C, where you can potentially damage hardware.
That, I think, is why we don't have a "Rule of most power".