...and find your click rates plummet. Which is fine if you're OK with that cost. But a lot of users aren't going to notice those links, let alone select them, copy them and paste them. If I already have to copy and paste a link, why not the actual page URL?
http://facebook.com/sharer.php?u=http://url-of-the-post
You use this to make regular links that users can click, instead of buttons loaded inside iframes, etc.