You write "if co-workers repeatedly use social media to air such complaints, one of two things must be happening: Either it’s become too hard or too scary to dissent privately, or you have the wrong people on staff. Or both." But there's a third scenario, which is that the institution ignores dissent generally or specifically. In some cases, with some issues, bringing public pressure on the organization, repeatedly is the only way to get it addressed.
You write "if co-workers repeatedly use social media to air such complaints, one of two things must be happening: Either it’s become too hard or too scary to dissent privately, or you have the wrong people on staff. Or both." But there's a third scenario, which is that the institution ignores dissent generally or specifically. In some cases, with some issues, bringing public pressure on the organization, repeatedly is the only way to get it addressed.