alt Hacker NewsWindows loader is part of the system ABI, and programs' libc(s) are loaded by it.
One of the ways Windows manages to support multiple libc's is by being careful not to mix allocators; if a system API you call allocates on your behalf, your libc can't free it, the system API will offer a function to free it.
Windows loader is certainly available to user programs though; LoadLibrary has been around longer than many developers.
LoadLibrary will also not be able to load arbitrary libraries compiled for newer versions of Windows though. Just like with gcc, Windows also does not guarantee forwards compatibility - because that would men freezing the feature set the system libraries provide.