I get the point of this service, but what does it offer a user can't achieve with a secondary gmail account and using "plus scheme" addresses like "joe.smith.s

I get the point of this service, but what does it offer a user can't achieve with a secondary gmail account and using "plus scheme" addresses like "joe.smith.secondary+hackernews@gmail.com"? Not to mention the cynical view that it's Yet Another Breach Target with potentially lots and lots of email addresses...