What are the use cases for web workers in mobile environments? I can't see any good reasons to be using up the viewers battery and limited prrocessing power tha

What are the use cases for web workers in mobile environments? I can't see any good reasons to be using up the viewers battery and limited prrocessing power that way other than for (maybe) backgrounding some of the processing for a web app. On a non-mobile note: If you use my computer to run your map-reduce job without asking me first; I don't like you.