Fact: Linux lets you mount CIFS file shares.
Question: Is the CIFS driver an in-kernel driver? Or is it a user-mode FUSE driver or something?
There’s a CIFS driver in the kernel, but there are also FUSE drivers capable of mounting CIFS shares: fusesmb, SMBNetFS, perhaps others.
If you mount shares using mount -t cifs, you’re using the kernel driver; if you mount shares through your desktop environment (e.g. by browsing to them in GNOME Files), you might be using a FUSE driver instead.
mount -t cifs is exactly what I'm doing.