The only reason I can think of is browser vendors losing faith in the standard being approved, therefore removing the implementation from their code.
To support this thought: W3C just removed both datetime
and datetime-local
from their working draft.
Browser vendors will eventually drop support of both of them.
According to html5test most of the current browsers removed support of both of the input types.
The latest development:
- The
datetime-local
is back on the draft; - The newer specs page doesn’t show
datetime
, but it does showdatetime-local
. It does sound like it is back on the map and going to be supported again!
Also take notice of this related post on Webmasters.SE: Is datetime-local removed from HTML 5.1?.