The convention to use bits per second is due to the fact that a bit was originally the single smallest signaling element included in an electrical exchange and was originally refered to as baud rate. So 300 baud was 300 bits per second and you can't divide that evenly by 8. Baud rates had nothing to do with the 8 bit per byte convention used to store data. Later they found ways to include multiples of bits in an electrical exchange to increase the data transfer rate, so the number of bits transfered is a multiple of the baud rate. Given this, the same baud rate could now express a wide variety of data exchange rates depending on how many bits are contained in a single electrical exchange so kbps is more meaningful to the user. Point is, bits is correct and bytes is not when expressing data transfer rates.