why mkdir can't create tree of dirs?

[Suliman via Digitalmars-d-learn]

On Tuesday, 9 February 2016 at 23:23:10 UTC, Jonathan M Davis 
wrote:
> On Tuesday, February 09, 2016 20:20:59 Suliman via 
> Digitalmars-d-learn wrote:
>> It's look like that I can only create one nesting level sub
>> folder, for example there is exists dir: D:\foo
>> I can't create dir D:\foo\bar\baz I can only create D:\foo\bar
>>
>> D:\foo\bar
>>
>> Is it's rational limit or it is bug? Here is error when I 
>> tried to folder in folder thet do not exists.
>>
>> It's not very handy to write all levels by hands...
>>
>> td.windows.syserror.WindowsException at C:\D\dmd2\windows\bin\..\..\src\phobos\stdfile.d(2048): F:\foo\imgs_projected\jma_vis\1602\123: ╨б╨╕╤Б╤В╨╡╨╝╨╡ ╨╜╨╡ ╤Г╨┤╨╨╡╤В╤Б╤П ╨╜╨░╨╣╤В╨╕ ╤Г╨║╨░╨╖╨░╨╜╨╜╤Л╨╣ ╨┐╤Г╤В╤М. (error 3)
>
> You can use std.file.mkdirRecurse instead of std.file.mkdir. 
> std.file.mkdirRecurse is similar to mkdir -p like 
> std.file.mkdir is similar to mkdir.
>
> - Jonathan M Davis

What profit to split it's in two functions? Why mkdir can't work 
in recursive mode?