Automatic subscriptions to "my" content

I think notifications should come automatically related to your own content. (I mean the site notifications, not email or SMS.)
So as the title says, notifications should come automatically when someone comments to your post, or comments to your comments.
Just like in social media, it is automatically on, user should not need to go to switch it on. Instead they could go switch it off.

I need this feature as automatic as possible. User should receive notifications by default but can go and turn it off if it bothers.

This can not move on until the questions have been discussed and brought to a conclusion.