Windows since NT uses a so-called hybrid kernel. This is where some parts of the system run in kernel mode, while other parts run in user mode. However, Windows can be stripped down pretty far, which is how you get IoT versions of it.
The traditional reason why people have avoided micro-kernels is there's a lot of overhead with message passing and system calls, since everything that's not the kernel has to jump through the usual user mode hoops.
EDIT: The Wikipedia literature seems to imply that Windows NT does use a microkernel, but the OS itself does not run as a "true" microkernel OS would.