Hypothetically, wouldn't really aggressive archiving accomplish the same task?
Have a 0-email inbox, and if you get something that you can't address immediately (but you can take care of later in the day), then you leave it in the inbox. In the meantime, anything you can act on in some way gets acted upon and then archived. By the end of the day you would ideally have just that email in your inbox (and even in a realistic world you might have a few tasks lingering in your inbox, but few enough that you can glance and see that "task" still there). Check your email at the end of the day and act on the things you needed to postpone for whatever reason (as well as pruning emails loitering in the inbox).
This requires, as previously said, really aggressive archiving, but since there's no difference between inbox and all-mail as far as I know (unless you use it as a search operator e.g. "from:friend@university.edu label:inbox"), it wouldn't be that big a cost (except that you would have to remember to archive or go through later and archive stuff).
I had been doing this somewhat organically for a while - tagging emails that didn't get filtered automatically and archiving them when there was nothing more for me to do with them - but when I disabled all of my filters (a misguided experiment I don't recommend anyone attempt) I stopped.