It clears email from your inbox without deleting it. It was a somewhat revolutionary concept when it launched, because back then most email providers severely constrained storage space, and keeping everything archived away was pretty much unheard of.
And gmail doesn't use anything called folders, but it has a variety of other organization tools, including labels, which I find far more effective, but others may not like as much.
And for everyone who has a fitbit, there is someone who doesn't. This notion that you NEED an Android/iOS to support all these gadgets really falls flat when you discover that most people probably don't even have those things.
Banking apps? Yep, I have those. Chromecast? No, I don't, but again my phone and the Microsoft wireless display stick work just fine together without downloading anything to the phone.
Even if we assume that every one of the 400 million Instagram users and 200 million Snapchat users and hundreds of millions of other users of these services all already fall into the pool of billion gmail users, that's still a pretty sizable market share to miss. And it makes it really hard for those who are influencers to recommend BlackBerry 10 when you don't know whether it will do everything the person might want it to do over the next roughly two years.
Your banking apps may be on BlackBerry 10, but not all of mine are. And Chromecasts are very different from the Microsoft product. And they work with a whole range of services, like mlb.tv, which aren't on BlackBerry 10.