I dont think anything wrong with sshfs. I like it as a simple zero config/administration
instant network access tool. Slowness comes from encryption, and on the faster
machine it 's not an issue. I remember some comparison found it
faster than nfs with encryption option turned on. Off course, nfs has finer file sharing/locking,
but it comes with much more effort put into administration.
Also I found that on BSDs many tools have blocked networking modules, though those were implemented. rclone, mplayer for example. I think the reason is fs compatibility in those
implentations. But again, sshfs was working already..
Edit: and not having enough eyes/hands for maintenance. It is probably main reason.