How is that weird? A semi-hidden API like this is a huge benefit to Microsoft itself, and a detriment to its competitors, or indeed, anyone who writes software

How is that weird? A semi-hidden API like this is a huge benefit to Microsoft itself, and a detriment to its competitors, or indeed, anyone who writes software that becomes a DLL in the next version of Windows. If you write to a documented API (Win32, GINA, etc) your code is slower and possibly less capable than it could be. If you write to the undocumented NT-native-API, you have to invest time and effort into understanding it, and risk having it change out from under you at the next rev. Microsoft internally, and/or favored partners, get to use the faster, capable native API. So, Windows developers have something of a dilemma to deal with, don't they? Also, I'm given to understand they're callable as C functions.