The C++17 bits are things proposed by people on the VC++ team, since verifying that something is actually implementable is an important part of writing a good proposal.
By my count, none of VC 2015 RTM's C++17 features will have been proposed by MS. N3922 auto and N4086 trigraphs were proposed by Googlers. Same for another Core feature that might be checked in. In the Library, I just checked in void_t, invoke(), and trivially copyable reference_wrapper, none of which I proposed (or anyone else at MS). I did propose auto_ptr/etc.'s removal which was voted into C++17, but it's too late for me to remove that stuff from 2015 RTM.