Eraserhead inhabits the same darkly comedic space as earlier abusurdist theatre, especially the work of Harold Pinter, but Lynch takes full advantage of his newly-chosen medium. There's no question as to why this groundbreaking nightmare, simultaneously overt and mysterious, is one of the most influential movies of all time.
"Several board members at the AFI were still opposed to producing such a surrealist work, but they acquiesced when Dean Frank Daniel threatened to resign if it was vetoed." Thank god.