Are you signed in? The top navbar is only present if you're signed in[1], otherwise you should see "Moments" as the top contents of Featured[2].
If you're signed in and don't see it perhaps when Moments first came out a couple years ago you installed one of the various addons to hide it and don't remember it?
I don't have it either. I have a 'moments' link on my profile page, not on my feed, but as I have not created any 'moments' for myself, it's just a blank page telling me what they are.