Plex the server is not based on XBMC/Kodi. Plex the server has supported reading files from network shares for a very very very (very) long time.
The Home Theater client was based on XBMC, but it only ever connected to the server.
The Home Theater client was based on XBMC, but it only ever connected to the server.
Though I still prefer Kodi for its FOSS-ness.