Dates are far more complex to manage than most people think. Even though a datepicker is something basic needed on most websites, it seems it needs a lot of effort to create a good one which works everywhere.
In theory they allow using the platform convention (i.e. on iOS the native datepicker is usually much nicer than whatever you can do in HTML).
Luckily Spartan (new Internet Explorer) will support it. Unfortunately given the recent track record of Safari development, I don't think we'll see support across all browsers anytime soon.
This is why I don't understand the incredibly bad support for the HTML date/time inputs (http://caniuse.com/#feat=input-datetime)
In theory they allow using the platform convention (i.e. on iOS the native datepicker is usually much nicer than whatever you can do in HTML).
Luckily Spartan (new Internet Explorer) will support it. Unfortunately given the recent track record of Safari development, I don't think we'll see support across all browsers anytime soon.