That was explained to. 3rd party icons are separated from 1st party icons. It's not in-house. Don't forget that all 3rd parties are at the end of the roster and before only the Clones(who notably were last minute additions by Sakurai, and were going to be alts first), and the Mii Fighters are far last on the Character Select Screen because they don't exist till you create them. So it was always 1st party, 3rd party, clones, Mii Fighters, and Random button. The data and the Character Select Screen literally separate them. ...Why is it that surprising? That pretty much answers your question.