I'm subscribing to that chakra theory until the finale proves otherwise.
I think there's a sort of escalation thing going on with Amon's targets, too. As if he's not just going around robbing people of their bending, but he's doing it systematically.
He first demonstrated his powers on the triads, who one could assume have weak mental constitution and would easily believe that their bending was removed. Next was Tahno and friends, who would probably prove more difficult, but it's completely obvious that Tahno was already aware of what Amon could do and was terrified of losing his bending and livelihood. This continues all the way up to Lin Bei Fong, one of the toughest characters in the series, who, between her men losing their bending and in light of everything else, submitted to the fact that Amon had to be legitimate.
I know it sounds iffy, but it also explains why he didn't remove Korra's bending the first chance he got aside from his martyrdom excuse. He didn't do it because he didn't know if he didn't want to risk trying and failing to remove her bending, or else his illusion of power would fade and people would start to doubt that he can actually take bending away permanently.
Basically, he played it safe to begin with and made a spectacle of himself at the Pro Bending finals because he wanted to make sure everyone knew what he was capable of and ensure that his ultra chi blocking would actually work on everybody.
Convoluted and probably reading too much into things, but it's just a thought.
From: Forceful_Dragon | #465
Part of me has always expected their bending was not permanently removed, but now that Lin got her bending removed in such a powerful way I think I would look back on that scene differently when it's confirmed it isn't permanent.
As far as she knew, it was permanent. The sacrifice doesn't mean any less, though the end result? Sure.
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I like how each new topic you make reveals such varied facets of your idiocy. - foolmo
[NO BARKLEY NO PEACE]