I remember reading once (but now I can't find the details, this may be apocryphal): a few browsers did try this for a while, but it turned out be a disaster for

I remember reading once (but now I can't find the details, this may be apocryphal): a few browsers did try this for a while, but it turned out be a disaster for certain sites. If, for example, you have a page loaded with a list of items, each of which has a delete link next to it (think PHPMyAdmin): what happens if the browser automatically sends a get request to every link it sees in order to prefetch the content? The server will just see this as a user clicking a link to the delete page and automatically delete the item. The solution to this is obviously that servers should obey the rules of HTTP methods better: GET is idempotent and doesn't change state, so it should be impossible to delete data just by clicking a link. Instead, you should at least need to submit a form via a POST request in some way. In practice, though, browsers need to deal with badly designed servers, which is why almost all of this prerendering, precaching, etc stuff requires an explicit opt-in from the website.