Python ≥ 3.6 requires (some features of) C99.
> Perhaps the reluctance to move to a more ‘modern’ C is that even C99 can’t legally buy a drink
Perhaps it's because MSVC didn't fully support anything newer.
(some of the changes) http://www.open-std.org/jtc1/sc22/wg14/www/newinc9x.htm
C99 support was added in VS2015 to the extent required by C++14, similarly C11 support was added in 2017 to the extent required by C++17.
You don't work in the enterprise domain which is VS’s core market, do you?
Usually it takes one year to upgrade to a new version, after its release.
We are already playing with 2017 for next year upgrade cycle.