Why always picking on the HD manufacturers? Your GigE network runs at 1,000,000,000 bits per second, not 1,073,741,824, what a scam!
Data transmissions are based on resonant frequencies of reference crystals, and have no fundamental connection to a binary counting system (except perhaps in terms of harmonics). Hard disk drives use sectors which at some basic level have to be addressed by a powers of two binary addressing system. This means that no matter what else you do with sector sizes or block sizes, the binary counting system *always* comes into the picture. Base 10 by contrast is the interloper there.
Memory is measured in multiples of powers of two because that's how the addressing works. Disks and network have no such fundamental limitations - they count in sectors and frames, which are themselves not necessarily powers of two.
Wrong, and wrong again. *All* computer peripherals transmit data to and from computers encoded in binary signals. It means that all computer based addressing is essentially binary. Back in the early years, some bit twiddling idiot tried to force a decimal system onto computers (see BCD) The whole thing was such a stupid idea it was pretty effectively dropped for almost everything except scientific computing, and even there it wouldn't really be necessary if those pesky scientists were half as smart as they think they are.