That said, it probably has something to do with earliest 5-bit and 6-bit text encodings that were very constrained wrt control characters, and often originating from punch cards where fixed-length or length-prefixed (https://en.wikipedia.org/wiki/Hollerith_constant) strings were more common. E.g. DEC SIXBIT didn't even have NUL: https://en.wikipedia.org/wiki/Six-bit_character_code
That said, it probably has something to do with earliest 5-bit and 6-bit text encodings that were very constrained wrt control characters, and often originating from punch cards where fixed-length or length-prefixed (https://en.wikipedia.org/wiki/Hollerith_constant) strings were more common. E.g. DEC SIXBIT didn't even have NUL: https://en.wikipedia.org/wiki/Six-bit_character_code