It is overkill, you're absolutely right about that. But that's the good thing about the webs, you can throw the stupidest ideas on the table and the let everyone flesh it out :D
Most times there are some few links that are very frequently clicked on; for example in Hacker News is usually the "next page" and the "threads". So if there is not one already there should be a way to specify some (obligatory?) preload pages.
In my opinion even that is overkill. Remember, in most cases it’s already instant. The return on investment (speed/requests) abruptly declines with brute preloading.
