Are you trying to make a pun with byte/bite relating to nibble? Because that's actually where the term nibble (referring to 4 bits) comes from, so I'm not sure such a pun even counts as a pun anymore. Or am I misinterpreting your comment?
I was wondering this as well. Probably when a new wave of people discovered the concept in the absence of the older wave? By contrast, "byte" has been in use continuously and widely.
The definition of a byte today is different than the definition of byte when those machines were manufactured. Just like how 'foot' is now standardized(*)
(* technically, a 'foot' is not a standard unit of measure but that's due to the long history of 'foot' not being standardized until relatively recently)