[jcranmer]

I'm dubious of this explanation because C itself largely postdates punched cards as a major medium of data storage, and some quick searches doesn't produce any evidence of people using punch cards with C or Unix.

[noosphr]

Ed was also line oriented.

Using regex to edit lines instead of typing them out was a step up, but not much of one.

Also my father definitely had C punch cards in the 80s.