@Moneo@SigHunter Networking came to be when there were lots of different implementations of a 'byte'. The PDP-10 was prevalent at the time the internet was being developed for example, which supported variable byte lengths of up to 36-bits per byte.
Network protocols had to support every device regardless of its byte size, so protocol specifications settled on bits as the lowest common unit size, while referring to 8-bit fields as 'octets' before 8-bit became the de facto standard byte length.