These are the cases where users are automatically subscribed, and how it works:
* Site owners, admins and mods: all traffic on the whole site.
Actually, this is incorrect.
To replicate the situation:
- Create a new site
- Have a look at the bottom & you will notice that you are not automatically watching the site, you need to do it manually
Personally, I prefer it this way (how it is already), but automatic-watching for site creator could have its advantages…