What about folks who pay-per-byte for network bandwidth?

[hassen1]

Basically, there are two ways of looking at this issue:

websites can already cause things to be silently downloaded using JS/DOM hacks.
prefetching is a browser feature; users should be able to disable it easily.
It is important that websites adopt <link> tag based prefetching instead of trying to roll-in silent downloading using various JS/DOM hacks. The <link> tag gives the browser the ability to know what sites are up to, and we can use this information to better prioritize document prefetching. The user preference to disable <link> tag prefetching may simply encourage websites to stick with JS/DOM hacks, and that would not be good for users. This is one reason why prefetching is enabled by default.