My youngest daughter simply doesn't understand the concept of a surprise. When asked to keep a secret something seems to build inside her, a something which simply cannot be contained, a something which must be voiced - albeit in a manner a 6 year old thinks is obtuse, elliptical, not-at-all likely to let the recipient know there's a thing awaiting…
She: "Daddy, we have a surprise…" and I rudely cut her off, explaining why she must STFU.
She's unstoppable though, learns nothing from recent history. It's easily forgivable at 6.
Facebook is the same. I post a link to something, Facebook simply cannot contain itself and produces a helpful preview of the page header, YouTube movie title, whatever… I'm not sure I can forgive Facebook as a 12-year-old though.
I suppose I could obscure the content behind a custom URL added at either my web site or via an URL shortening service (presuming Facebook doesn't automatically expand those.)
But why should I have to‽
I 'get' that security is an issue these days so having some indication of what's about to happen is 'safety-conscious'; I know, as the average attention span diminishes towards zero, that people like to see a preview of what they're about see (especially previews.)
But from where are our future Rickrolls likely to come - if Facebook first shapes then reinforces our habits?