Is there any reason to believe that cheating is something that started recently? Is there any reason to believe that the ROM loaded on every single original Donkey Kong cabinet is exactly the same? Is there any reason to believe that the components on every single original Donkey Kong cabinet perform the same?

If you look at the sports world you have, more or less, the acceptance that cheating happens, the components change, training regimens change, etc. Professional baseball has comprehensive statistics dating back to the 1860s and the result is that people have divided the sport into eras, and when you compare players in different eras you don't look at the stats alone, you compare how they performed relative to their peers, etc.

A "high score" list that ignores the reality of change is worthless.