Seems like most of the LE team is using windows as main OS
Not me. Ubuntu is my daily driver.
Now I understand why nfs-server in LE isn't available.
Not really. Kodi (and LibreELEC) is designed to be a application CLIENT. It is not meant to be a server. It does have SMB because Windows supports it basically as its only sharin, Linux can do both SMB and NFS quite easily. NFS server is not implement in LE because it would add to LibreELEC becoming bloated.