That only applies if loss of data/access to data is a greater problem for you than exposure of the data. Spreading it into multiple locations/services gives more choices for an attacker to breach to expose it and they only need to get into one of them.
If you have six and one gets hacked, the other five are still secure. If you use the same site for everything, that probably increases the risk of being hacked (because a single site gives your activity more exposure), and when you are hacked, you lose all your data, not just 1/6th.
Most comparative reviews find Gmail slightly better, but there's very little in it.
http://www.maximumpc.com/best_email_service_2013 http://mashable.com/2012/08/14/outlook-vs-gmail/ http://www.pcworld.com/article/2010598/gmail-vs-outlook-com-... http://lifehacker.com/5931621/outlook-vs-gmail-a-feature+by+...
It's not.
I've tried for days to login to Outlook.com, and verification text messages aren't coming through.
I finally had to start the email recovery procedure, which requires a mandatory 30 day waiting period. Sigh.