They were black hat, but they had to do it right to stay in business. Isn't that valuable advice? How to not get your account closed?
They had to find a way to get around rules, you mean? To cheat a system, to break rules, not because they're harmful, but because the rule breaker wants an easier, quicker, better way to steal money?
Amazon already gives us valuable advice to avoid getting our accounts terminated. No workarounds are needed. No thousand dollar courses to learn how to game the system. No easy, sneaky way to get ahead of anyone else. There are thousands of people who follow the rules and make very good money. Some make winning lottery ticket money. They don't have to worry about getting caught at something they shouldn't be doing. They don't have to find a way to break any rules.
Anyone who thinks finding ways around the rules aren't in this for the writing, they're looking for easy money, and they don't care that every time they get caught, Amazon amps up the rules and makes it harder and harder for honest people to find their dream as a writer. We've seen it with KU, we've seen it with simple things like tags, or being able to add images to our sales page, or every other little thing that made it better for those of us willing to follow the terms of the contract we signed.
But you keep on, dig that hole deeper, keep finding excuses for the cheaters. I for one don't care about you, or anyone like you. When you get caught, don't come looking for sympathy here, because you won't get it. Except maybe from that other person who signs up just to support something that's wrong. That will be your solace.