Actually, I see inbox zero (or near zero - I try to keep it under 10) as a time saver. It means I can instantly look at my inbox and see what items I need to work on.
If you just keep everything in your inbox, it means you need to click on a button to sort by starred emails. Also you need to star any emails you need to work on. Most of my emails take a while to respond to - I like to think about them for a while before responding. With your method I wouldn't be able to do that - I have to either respond to all my emails after reading them, or else star all my emails as 'needing work' until I have time to respond.
Keeping only a few items in my inbox that I need to work on is the most efficient way of working, at least for me.
If you just keep everything in your inbox, it means you need to click on a button to sort by starred emails. Also you need to star any emails you need to work on. Most of my emails take a while to respond to - I like to think about them for a while before responding. With your method I wouldn't be able to do that - I have to either respond to all my emails after reading them, or else star all my emails as 'needing work' until I have time to respond.
Keeping only a few items in my inbox that I need to work on is the most efficient way of working, at least for me.