Grin seemed to bring in some sort of "shuffling" method to reduce traceability by allowing accounts/addresses to move funds and make them less traceable - I don't think mimble wimble fully had a complete level of privacy before that but I could be wrong.
WoW the mwixnet idea is really clever. It reminds me of zero knowledge ceremonies where only one person has, to be honest for it to work. Thanks for the link!