Browsers Browsers EVERYWHERE!

I noticed today that any app, for example Facebook, cannot open links in the Safari browser.   The same is true for skype, google+, and i'm sure any number of other apps?

Why?

This essentially makes each app have its own browser.   What if somebody sends you a cool link in facebook and you click on it, it moves to another page within the facebook app and displays the web contact.   What if you want to bookmark it?   You would have to copy the text of the link, paste it in your Safari browser, then bookmark it.

What if you click a link in Facebook your friend sends you about Chuck Norris, and you want to find out more about Chuck Norris?   Close down your Facebook browser, open Safari and search for Chuck Norris (hint: you'll never find him)

In Android, ANY app can interact with any other app.   When you click a link in the Facebook app, it opens your system browser and you have full access to the system browser.    The iPhone method opens a "frame" of that browser within the app.   See the picture attached to this post...

Why is this so hard?