But therein lies the problem: a tool that you don't use often (hence a low number of ad impressions), and an unobtrusive ad that you might not even see, let alo

But therein lies the problem: a tool that you don't use often (hence a low number of ad impressions), and an unobtrusive ad that you might not even see, let alone click. That's unlikely to earn enough money to be worth it. The developer either has to drop the advertising revenue model and try another, or crank the ad model to questionable ethics. Sadly, some developers opt to do the latter.