Because of preorders. It'll be easy to get #1 from now on.
Getting a song from a pre-order isn't a new thing.
People are still paying for the song as an individual (hence why it counts). Not every song that comes from a pre-order goes Top 10, let alone #1 in 70 countries.
People will go to such ridiculous lengths to drag Gaga. It's impressive no matter how you cut it.
I still don't buy the pre-order thing. It doesn't explain why Walking On Air and Dark Horse got the strange boosts at separate times. It doesn't explain why Bieber is getting them.