I don't believe any of that.
I don't believe any of that. I've had multiple mazda's, all the way back to a 2006 mazda3 hatch, and never had any issues. 2010 miata, 2018 mazda3 hatch, 2008 cx7. My mom's optima is the one that runs rough at idle, while all my mazdas felt so smooth you'd forget they are running. Plus, mazda topped CR's reliability list. Seems if what you're saying is true, you must be the only one experiencing those issues, because no one else is.