At the very basic level of it, advertising is giving out the information that your product exists, because otherwise, nobody would even know its existence.
Your example for Apple is very good, it's very highly probable that some persons only switch to newer iPhones when they hear the news it exists and see the keynotes/articles about it, even though there is nothing wrong with their phone, and they may not be thinking about changing it.
For my wife, the pods are a lifestyle upgrade over the regular powdered pour out detergent. The convenience and effort saved justifies the more expensive packaging.
I'm a firm believer in adopting new processes or products that reduce the amount of time required to perform my daily functions. They pay off in the long run.
When smoking ads were banned, profits for cigarette companies went up, because they didn't have to spend money on marketing anymore. Addicts still kept buying them anyway. Previously, smoking ads were to get people to buy your brand rather than some competing brand.
I’m sure there are pretty of studies out there.
The Tide example here makes me feel a little bit weird, because Tide pods in particular are a pretty bad deal for laundry detergent. If people are buying Tide pods instead of generic laundry detergent, it seems to me that the advertising isn't just shifting money around, it's actually increasing spending. But it could just be bad instincts, I don't know of any actual real research on the topic.
Another way of phrasing this -- if Apple stopped advertising iPhones, some Apple users would shift over to Android, which (ignoring cost differences) theoretically would just mean they gave the same money to someone else. But would there be another contingent that stayed on iPhone and just stopped buying new hardware every year? How large would a contingent like that be?