Windows has other user space file systems, and has for a long time. OpenAFS goes all the way back to 2000, and had a windows 95 client even[0].

Comparing libfuse to Dokan is like comparing fat16 to HAMMER. It's recent, but not the first by any stretch

https://github.com/openafs/openafs/tree/ba3d4666cbd19b56bcec...