And here is a pretty clear example of alignment as stick. The idea that without mechanical alignment players are incapable of actually playing their characters in a consistent manner. Zero trust of the player.
So Imaro and N'raac. Do you agree with Dannorn that in the absence of mechanical alignment players will automatically choose the most expedient option over playing in character?
Are you aware that there are gradations between "zero" and "automatically"?
No, I do not believe that players will automatically choose the most expedient option over playing in character. Neither do I believe it is automatic that alignment will be used by the GM as a stick to beat players into submission.
I do believe that rationalizations often occur to suggest that what is most expedient is, indeed, playing in character. And if alignments are not cosmological forces that are defined objectively, outside the decisionmaking process of the PC, playing in character may well go against alignment. That's why a single inconsistent act, or even an inconsistent personality trait or two (consistent to the character, but inconsistent with his alignment) does not mean a change of alignment overall. It's also why a character's alignment can change - he's simply not following the precepts of LG because he is following his character.
You seem to reject outright the possibility that a player can "play in character" and, as a result, play inconsistently with his alignment. If we take your approach, then each alignment is defined by how the character claiming it behaves - so get the player to name his own unique alignment. He can be Greedy-Violent, or Pious-StuckUp. Everyone needs their own, since they are deemed to always be perfectly playing to that alignment, so two people can only share one if they share a hive mind.
Alignment as a real, cosmological force means it is external to the character, just like the rest of his environment. The player can't decide the precepts of the alignment, only he extent to which his character, played in character, will adhere to those precepts.