You are missing my point: the raw bit rate of the network is not the rate of file transfers. There is a bunch of logic around the raw bits in the wire that make it mich more complicated than dividing by 8
Actually, the real point is that the average person doesn't need engineering precision which is my original point. Whether it's 60sec or 65sec to xfer a file doesn't matter to them. Engineers always like to argue precision to justify complexity and lose sight of the larger picture (eg. consumers/majority matter).
btw- how does expression it in bits v/s bytes help you with your desired calculations?
You brought up math. I never disputed that 100MB / 12.5MByte/s is slightly easier than 100MB / 100Mbit/s. I'm just saying that calculation, in both forms, gives a very inaccurate answer to how long a file transfer will take, which is what you brought up as the big reason.
An easier and better answer is what jdiez17 described: just divide by 10. I.e. 100Mbit/s link speed is approximate 10MB/s of data transfer.
btw- how does expression it in bits v/s bytes help you with your desired calculations?