Yeah, comparing Spielberg's "snubs" to Bigelow's and Affleck's is ridiculous since they were both considered possibilities to win, Affleck less so, but certainly possible.
Spielberg has only ever been the frontrunner to win for Schindler's List and Saving Private Ryan and now Lincoln.
Not sure about The Color Purple though? His snub was shocking, but I don't know about him being a frontrunner that year, especially since it went home empty handed.
I will never be upset about his snub though since it got Kurosawa his first and only Director nomination, which was awesome.