Why didn't Kingdoms of Amalur download into Steam?

I bought the disc, installed it on my computer, and it made me download Origin instead of downloading it into Steam. I have never had this problem before, and I want to know how to fix it. How can I move it into Steam?Why didn't Kingdoms of Amalur download into Steam?
Active serial key on steam, easy.Why didn't Kingdoms of Amalur download into Steam?
Go to your Games Library. Add a Game (bottom left). Add a Non-Steam game. Find the game in the program list. You'll now be able to play it through Steam.Why didn't Kingdoms of Amalur download into Steam?
It's an EA game, EA is boycotting Steam.
Not every game is a Steam game. KoA is published by EA, which owns Origin, so that's what it uses.

EDIT: OK, so not every game that's sold on Steam has retail keys that can be redeemed on Steam. That list is actually pretty short outside of actual SteamWorks or Valve games. There's no way to add it to Steam (other than as a non-Steam game) without buying it through Steam.