Examples:
- My girlfriend keeps asking me to sign up for snail mail advertisements (e.g. discounts at local stores).
- When I was performing maintenance on my mother's laptop, I saw an annoying "daily offers" ad popup from her virus scanner. I immediately went for the "Don't show this again" checkbox, but my mother stopped me in my tracks. "Don't do that! Those daily offers are useful!"
It blew my mind.
If you are in a very competitive market for user acquisition - mobile game, Uber, crowd based delivery service, etc - 1 or 2 percentage points in behavior can be a really damn big deal. 1 or 2% uninstalling your app every week is enough to kill your viral coefficient. It would have been enough to kill Facebook.
You are notch and you just made Minecraft? Probably doesn't matter.
For myself, while I'm annoyed at notifications, they also work on me for the apps I care about. (For apps I don't care about, I wasn't using them anyway.)