When life calls for causal analysis

Long-time reader Antonio R. sent me to this thread about plummeting subscriptions suffered by a Substack user. Her last sentence was: "what good are followers when follower growth seems correlated with losing paid subs??"While stated as a "correlation," the wording reflects a mild form of causal creep. Her mental model underlines a causal model – followers cause paid subscribers. This mental model is widespread in marketing circles. It's got a name: the "marketing funnel". Marketers believe that if they stuff the funnel from one end with followers (substitute eyeballs, free users, free trialers, etc.), they should find more paid members out the other end. The process is called "conversion," endowed with a metric called "conversion rate".Conversion can be organic, as in self-motivated, but surely, some users are induced by a marketing action, such as a conversion offer (20% off if you sign up now type of thing). Data scientists (I'm one of those) may even devise scientific experiments…