Wuyizidi is speaking from the perspective of Chinese internal and external arts. last time I checked martial arts from other cultures and countries don't have such a designation. On that basis any comparison is destined to be problematic.
It's not even a case of "we only do it like this, they only do it like that", in any case. It's often far more about what approach and what emphasis (a system/style(s)) training undergoes and what that results in. It's crazy to think end results in fighting are going to be wildly different, other than stylistic and or qualitative.
Further if you just took a single boxing division, you'll be able to figure that despite everything being known and out there doesn't result in everyone being equal, having the same style, power etc.
So all in all, neither partisan internal/external argument is ever going to be clear cut. Because other than the core training modality which is the most extreme dual distinction there is always crossover. As indeed even in the most extreme dual distinction there is still the dot of the other within. And from there that dot can only increase.