Someone help explain to me how shorcuts for text replacement are optional in iOS

http://imgur.com/sHfs3Jn

After years of infuriating auto-corrects on the iPad, I've recently turned it off completely. The few typos I get are far less irritating to correct than the times it messes up what I'm actually trying to type.

One of the things I did have to do to save time was setup shortcuts for words that use apostrophes. It'd take too long to go and add the apostrophes for them each time. I noticed while doing this that it says shortcuts are optional. This just doesn't make sense to me. Without a shortcut it would have no way of knowing when you want to type it.

Is this just something they've missed or am I actually missing something here?

Oh and another thing that annoys me about the way shortcuts work is that they're still activated in the address bar in Safari. When I'm typing im for Imgur, for example, and it suggests the full address to me, tapping enter will change it to I'm instead, and search Google. Infuriating.