Completely agree with everyone above. Tabs are such a critical part of evernote. I also didn't realize they existed until a couple years into using the app, but they were then a game changer once discovered, and are now an essential part of my minute-by-minute workflow. If they're underused, I would suggest that it's because it's almost a hidden feature (at least, it seemed that way for me) - not because it's not extremely powerful and loved by those who use it.
I have reinstalled Evernote Legacy for now as this is so crucial to my daily ops. The new app is more aesthetic though, I'll give it that!