We all know it's an inaccurate term. For multiple reasons. It's just a convenient umbrella term for eastern martial arts
I agree with this part. It is a convenient term that, if we agree on it, makes referring to these arts (that do have something in common) easier. As to what they have in common IMO is "tradition," historically linked to the environment in which it evolved and reflective of that culture.
I see karate and boxing as good contrasting historical, cultural, evolutionary examples. Consider these influences and if they
significantly contributed to each of these two fighting methods as they exist today:
Exposure to long international influence thru trade and cultural exchange contributing to the art's evolution and development - karate, yes - boxing, no.
Effects of military conquests, the victor imposing its politics and culture that affected the art - karate, yes - boxing no.
Spiritual/philosophical concepts that over time influenced the nature of the art - karate, yes - boxing, no.
Changes in basic societal needs that brought about evolution of the art - karate, yes - boxing, no.
All of the above (and other things) combined to create karate as an art that reflected the culture in which it evolved. In other words, tradition. Boxing in this respect is much different than karate with its long and complex history.
China's empty hand TMA is unique to China, Okinawa's is unique to Okinawa, Japan's is unique to Japan, and the same for Korea. Each country's empty hand combat art reflects its culture and history. Boxing looks pretty much the same in China, Japan, Cuba, USA, France, Mexico and everywhere else. It doesn't reflect a cultural tradition.
This is not to demean boxing at all, it's just a different kind of thing, that for all the reasons above, I'd not put into the same box as TMA.