They do actually serve the purpose of catching a lot of tar, not just tobacco itself. Which I would assume does have some positive impact for the smoker not getting as much tar through to their body. Although its obviously a negligible benefit in comparison to just not smoking, but that seems reductive. Just like how they talk about ecigs. Harm reduction is a pretty valuable perspective, but for some reason people only view tobacco products from an “abstinence or bust” standpoint.

In the pre-filter days, when people used those long Pink Panther style cigarette holders, a lot of the holders were designed to fit another cigarette inside of it. The second cigarette acted as a kind of tar filter for the cigarette being smoked. When I was young I bought an old cigarette holder at an antique mall and it still had a cigarette inside it from who knows how many decades prior