ubiquitous suppression of good sense

Ubiquitous, at least as used here, doesn't mean in absolutely every case or instance. Rather it means so common as to be found at nearly every turn, in nearly every context, and to be more surprising by virtue of absence than presence.

Good sense is what common sense might be if people were both brighter and braver than they are, possessing the capacity and willingness to examine their own beliefs critically and sometimes discard them as baseless.

Suppression is slippery, more commonly a matter of denying traction than of pressing confrontation. It takes many forms, but they mostly boil down to ‘We don't have to listen to what you say because ____’ with the blank requiring nothing more substantial than ‘we don't want to.’

People don't have to listen to each other, of course, except perhaps when one is in a position to do harm to another, which is more likely to result in listening for intent rather than for content.

In fact, listening to other people is about as apt to steer you wrong as otherwise. If they aren't lying to you, or attempting to distract you from something more important, there's a good chance they're mistaken, or confused, or deluded. It's really hard to know how to take what another says without having at least some idea about why they're saying it.

Nevertheless, refusal to hear what another (usually just one other) has to say is at least occasionally a missed opportunity for growth.

Thankfully, all of this simply doesn't apply to the sort of mundane conversation that fills much of the day for most of us, where the stakes aren't high enough to bother. Otherwise we'd all be incapacitated by neurosis.