For me, and many ex-evangelicals like me, a crucial part in our deconversion involved respectful conversations with other-minded people who provided arguments and didn't assume I was just a dumb religious nutjob.
I'm sure it must've been difficult sometimes for these people to deal with my, in hindsight, rather less than stellar arguments in favor of things like creationism or my logical proofs of God's existence. But they did a good thing, and I wish there was more of that.
A conversation can have much more of an effect than might be immediately apparent. People don't want to lose face; it took me years of sweeping doubt under the rug before I had to admit that my beliefs weren't tenable anymore, and I know many like me. And yet the actual people who played a role in this might never know how much of an impact they made.
Furthermore, even if someone remains staunchly 'ignorant' (which of course happens quite a lot), these respectful conversations are never fully isolated. Whether it is bystanders who maybe do take the arguments to heart, or later conversations between the ignorant person and others, I think every little bit of 'respectful connection' matters, and more than it appears.
If, for example, scientists started arguing with flat-earthers, publishing op-eds "The World is rather round" etc., the flat earth conspiracy theory would stand to gain from it. Part of that is the unfortunate effect that for a certain demographic, anything said by what they perceive to be the "establishment" is reflexively opposed.
I believe the wish to "silence" some viewpoints is often misunderstood as an attempt to be spared some supposed personal pain from being exposed to it (the "safe space" idea). But, more often than not, it is actually an attempt to fight it, using a method that has a track record at least as good as engaging with it: making someone a social outcast when they, for example, advocate for another holocaust obviously comes with high costs for that person. It's a potent tool to change people's behaviour, and unlike laws, it's "strength" can be adapted with almost limitless flexibility.
It's the same mechanism that everyone uses when, for example, no longer inviting that one relative who always gets drunk and starts a fight, or that child that can't share their toys.
The problem I see is that the efficacy of shaming or engaging depends entirely on context.
For example, I think shaming racists on a societal level can be quite effective, if not necessary. Because I do believe much of our current 'liberal' society is a thin veneer over essentially the same kinds of people that have done terrible things through racist beliefs even in recent time. We need to fight to keep that veneer from chipping away too much, and perhaps to discover ways to make it less than a thin veneer.
But shaming a young-earth creationist colleague is likely to have little positive effect (to the degree that these things can be quantified, of course). Said colleague has a sufficiently cohesive, comprehensive social world where their ideas are perfectly legitimate. I'd say in this case the effective approach, if one cares enough of course, is respectful engagement. I've seen it work.
But... in a society where young-earth creationists are sufficiently large to significantly affect your reality, well, perhaps more of a fighting approach is appropriate, at the cost of changing the mind of one person at a time.
Obviously I can't prove any of this. I just know that I've seen overt skinheads and very serious Christians (myself having been the latter until well in my twenties) change their mind and while shaming them might've had some effect, in the context of Dutch society at least, engaging them was by far the most effective.
So personally I try to take a two-pronged approach. Shame/societal pressure in the aggregate, and respectful engagement, even with ideas that I find repulsive, on the personal level. I'm still very much in the dark as to what the right mix is, and what my role in all of that is in the first place, but this is my current approach. I do think you make a good point though, to be clear.
