Memes, when done well, can be good to convey a simple argument, poke a hole in an argument, or simply provoke thought, but I think you're right that actual information is better at changing minds. Memes and infographics are effective as a way of getting a foot in the door, and knowledge makes the sale.

Another function of memes is to boost morale among people who share beliefs, though these same memes can sometimes backfire by embattling those who don't share those beliefs, causing them to "double down" or become further entrenched in their positions.