Why do speeds still get quoted in bits per second?
Cuz the transmission is in bits. Not all the bits that are transmitted are actual data that you would see on your PC; some are protocol overheads (say about 17%), like the addresses of the sender and destination.
So when you download a file to your PC and you see it measured in Bytes, more bits than 8 x its Byte size were transferred to you over ADSL and the Net, and those bits have to fit within your Bandwidth (i.e. Sync Speed).
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 19 Meg WBC