I just thought of something. Ok so Amon uses blood bending to take away someones bending. Regular Equalists baddies block your flow of chi. So Amon must block the blood as he would do chi. Or chi could even be blood. But your probably like SOOOO.
Maybe a non-bender's chi is block like that so thats why they can't bend. So technically everybody can bend. So maybe if you could use blood bending to unlock the flow of chi in a non- bender they could bend.