Two points to be added— first of all, Frankenstein was Dr. Victor Frankenstein’s surname, and the creature was in a sense his son. Therefore, the monster was also Frankenstein.
Second, in meddling with things beyond his comprehension, creating new life and rejecting it because it failed to meet his standards and thereby dooming it to face attacks and rejection from the entire world, was Dr. Frankenstein not the true monster?
It may have some bearing in reality. When one covers up the area around their eyes with a little mask or even glasses, scientists have found it becomes significantly harder to identify them. Even security cameras have more trouble. I suppose that explains why nobody ever made the connection between Clark Kent and Superman.
Hogfather (2006)