If we don't mind about loosing our changes, then can we disable logging for DML? This is a question I've heard a lot. Ok, you don't need to recover your changes but Oracle may want to recover the consistency of its datafiles anyway. And that's why datafiles blocks changed though the buffer cache always generate redo.
But yes, in 12c you can do DML and generate only minimal redo. All DML: even updates and deletes. And that post is not about underscore parameters that allows corruption.