Around the same time DirectX 12 is being released but this begs the question as to why there is such a thing as DirectX 11.3
What this might mean is DirectX 12 is limited to Windows 8+
So really the question I should be asking instead is why is DirectX 12 a thing.
If DirectX 12 is not on windows 7 you will see the same sort of split you had back between Diretx 9 ( XP ) and DirectX10 ( Vista+ )
To this day I usally play games in DirectX 9 mode as in most cases you get better preformace. Some games DirectX 11 is better ( Civ 5 )