How I wish truth did matter. In what time period are you referring? Clearly, in 2020, truth at best is tolerated. When you have people with photo/video evidence of someone saying something, but then argue with you that it didn't happen or that's not what was actually said, the truth is no longer relevant. So the question then becomes "Whose truth matters?" In an era of post-truth with concepts of 'alternative facts', truth is best describe as "what you believe is truth".
If your idea if truth is such that it can be dictated by political will, then you don't understand what makes truth special. It is special almost wholly due to its resilience to narrative, and it is incredibly bold or stupid to try to discount it through those means.
It doesn't even need to be political. We have people that believe in a flat earth to this day. If you go through life expecting people to accept true as true, then you will be sadly un-armed for real-life experiences. There are people that are absolutely unwilling to accept that what they currently believe is not accurate, and will not listen to any reasoning what so ever.
Allow me to paraphrase a concept from Tolkien: evil doesn't win because it's a superior force, it wins because it convinces you that it's already won. "Look over there, evil wins. Look here, evil already won. Evil always wins, that's the way it has always been. You can't fight it so give up."
You can't win by spreading evil's messages, even sarcastically. You win by being a superior force and never giving up. People's credibility should actually suffer when they do or say things that are incredible, and people who appeal to us with facts and compassion should be rewarded.
There are fights worth having, and then there are fights that are worth walking away from. If someone starts spouting off garbage, I just walk away and cut ties with them. I'm well past arguing over stupidity. You can tell when someone is unreasonable pretty quickly. However, when someone responds in a way that says they are willing to at least consider an opposing view, I will have a conversation. I enjoy those conversations even if no view points are changed at the end. That's the way it should work. See, I just said should as well.
But what if they don't want a conversation? What if they want a "silent majority" that they will then claim to represent? What if they interpret a lack of resistance as evidence of support?
You may not be changing people's minds outright, but you do have some impact on the strength of their convictions, and their sense of how broadly held they are.
If someone doesn't want that conversation, then it doesn't happen. I don't strap someone to a chair with toothpicks under their eyelids. I reserve that when getting people to watch my short films!
Edit: Conversations about differing/opposing view points isn't always about changing minds. It just helps to get to know someone. If someone tells me they are vegetarian, I don't launch into why I'm not. However, I will make the mental note to not ask them to join me for dinner at the local steak house. If I want to have dinner with them, it helps me plan an appropriate place that they would be okay with as well.