Rule #1 of bans.

Every single person banned for legitimate reasons (buying gil, botting, exploiting, etc.) will claim innocence 100% of the time in order to scare up mass hysteria and try to get their ban overturned, or simply to spite the company that caught them with their hand in the cookie jar.

Do innocent people occasionally get banned? Yes
Should you believe every single person claiming to be banned wrongfully? Definitely not