Then fix them and move on. If you take that approach, there'll be no need to gag your people. They can babble to their hearts' content. But old habits are hard to break, and often employees continue to handle complaints, quality problems, etc. outside the Corrective Action system. This kind of thing pops up elsewhere, too.
People continue to buy on an informal basis, from unapproved vendors.
New employees come on board without going through the documented training process. Effective internal quality audits should catch these things. But management must be vigilant too. Accept less than full compliance with the system. I like this.