For many years, NTFS support (via a combination of a kernel driver and the mount_ntfs command) were considered
experimental, and only read/only access was supported. The mount command was always present, but the admin had to configure and build a custom, unsupported kernel.
With 4.9, NTFS was added to the i386 and amd64 kernels by default. Because this no longer required a custom kernel, the status of NTFS, still read-only, went from
experimental to
supported.
The comment in the commit was in regards to the future possibility of revising the driver to permit read/write access. This did not come to pass. However,
FUSE support was added (intially and experimentally) to OpenBSD at 5.4, and the ntfs_3g FUSE driver was added to the ports tree.
There have been
many significant improvements to FUSE support after 5.4. Along with functional improvements since, FUSE was
experimental with 5.4, and it would require both a custom kernel and a custom library build in order to enable its operation.
If you are considering using ntfs_3g, you should upgrade to at least 5.5-release.