Arguably all these other subsystems shouldn't be in the Kernel either but that's a different topic :)

There are quite a few benefits to doing these things in userspace over the Kernel, not really necessarily just because of the code size:

- The code is much easier to write and debug, you just write code like you always would.

- Bugs don't have the possibility to taking down your entire system or introduce vulnerabilities

- Especially on Windows, everyone can do this without requiring an impossible to get driver signing certificate