It would appear that too many notifications are added to the feed for certain events, making it difficult to sort the wheat from the chaff.
Take the example of this annoying spammer creating a post:
Aside from the fact he's a waste of oxygen, that's more than one whole screen of notifications for a post creation and quick edit (less than a minute after posting). Also, I don't see any replies, so perhaps the "replied to a post" notification is superflouous. Perhaps these could be condensed; do we need to know who started watching each post - it might make more sense to display that on the post page; "being watched by..."