The gist of it: The Equalists did not arise out of a vacuum, but the show also has no evidence of systematic oppression. Rather I argue that the Equalists were a non-bender gang that gained power because the United Republic failed as a government and as a community, leaving non-benders without protection and support. This flaw in the UR is a problem the show should deal with in Book 2 and beyond, and a good job for Korra to handle as the Avatar.
( Here's the extended version )
( Here's the extended version )