In my opinion it's not just a PM who wants to get promoted, in many cases it's also misaligned interests of consumers and app makers. In the Economist example,

In my opinion it's not just a PM who wants to get promoted, in many cases it's also misaligned interests of consumers and app makers. In the Economist example, the consumer might just want to resume that article they couldn't finish and later be done with it, but the app makers might want to "maximize engagement" by showing you all those daily news every single time you open the app.