DLNA/UPnP stuff in Kodi is only pushed via the Video and/or Music Library, afaik.
If you want no library but simply files only, use something like MiniDLNA. That tool supports video, music, and pictures.
We tested a MiniDLNA addon for a Kodi Leia LibreELEC build, and it seemed to do the job. I don't know if it's been entered into the repository already.
Thank you!
You're right, after deleting all removable default library categories from the menu, I mapped the undeletable "Videos" category on LE to the "source" being my Media Server (i.e. MDS) on Synology NAS (which already runs a media server plugin) across DLNA - as opposed to Samba or local file system. I also enabled "control LE from external devices" in the menu - to make LE box visible on LAN as a DLNA device.
This finally worked, but the way KODI announces itself on the network as a DLNA Media Renderer (i.e. MDR) is kind of flakey. Sometimes KODI flips out and I can't see it in the selectable DLNA devices menu on my BubbleUPnP controller, - as opposed to my Sony BD, Synology NAS or my laptop which are always there, 24x7. Why is that??
I don't want to store files on my LE box, nor manage the media library from within LE UI on TV screen. The whole idea is to decouple the MDR from the MDS in KODI LE as two separate, optional modules and let users install just the MDR module, so that the net effect is a DIY non-proprietary network "dlna" media player. An analogy would be, using a pre- and power amplifiers, as opposed to integrated amp.
The idea is to use the touch screen on my mobile phone (or tablet) with BubbleUPnP as media library browser and playback controller - without the need to find the remote and turn on the TV and navigate the LE UI with k/b or mouse (I don't have a NUC remote) - to play music or videos.
All my "media library" needs are already fulfilled by Synology RT2600, which runs a DLNA media server and a torrent client, saving files locally to attached USB disk, without pushing files out to my laptop across WiFi. I can navigate and play back any files in my media library using my phone with BubbleUPnP. When I listen to music, I don't even need to turn on my plasma TV (which has already suffered from burn-in.) to see LE's UI on my TV screen. I just pick up my phone, open BubbleUPnP, select the preferred Renderer, select the preferred Library, go to Library, browse to the video or music file, and press Play. I can also select next/previous, pause, stop and adjust the volume. BubbleUPnP shows me the artwork embedded in my music files (FLAC, Mp3) - both as thumbnails in Library view and Playing Now. For video, it allows to resume or restart after stop. Disclaimer - I don't work for BubbleUPnP, I just like it - it does exactly what I want, without bloating with unused functions.
Personally, the concept of an AIO HTPC (+ keyboard/mouse/BT/IR remote) - is dated. I don't want my router to have HDMI for playback, nor do I want my "HDMI player" to store and manage files in the media library. I want to ditch all clunky IR remotes and operate my whole home theatre from 1 device - my mobile phone, lying on the couch 
Has anyone tried forking out / modding LE to make it a simple DLNA Renderer version, along the lines I've described above?
This should be relatively easy to modify the installation script and make it a 2-step process:
1) Install LE Client (MDR)
2) Install LE Server (MDS) - if you need it