Many of the issues with DLNA/UPNP vs. RAAT may have had to do with very poor implementations when networked digital audio first became a possibility.
I remember trying to use a version of Foobar’s DLNA server with a Popcorn Box (network media player) back in the early 2000s and being dismayed that you could load a playlist and start the server but then could not modify the playlist at all - it just played through as initiated unless you killed the process on either end. Then there were all the issues with gapless playback and one format working fine while another choked the system. You could make it work but it wasn’t nearly as reliable or easy to use as just straight playback from a single device without beaming the media stream through the network.
These may not be inherent in DLNA so much as half-done implementations and compatibility between implementations. It seems like Plex does pretty well for folks when using both a Plex server and a Plex client.
Until I saw Roon’s signal path display, I’d never seen such a good trouble-shooting and quality-confirming tool. Maybe it is like the blue light on an MQA DAC, but I do feel better when I see the white or purple indicator that confirms bit perfect quality.
So i think the real answer is that DLNA given the proper love and attention may work reasonably well on implementations meant to work together. RAAT already assures this because it is either RAAT capable or not, for the most part. That also means you get all the signalling necessary for the signal path to be displayed accurately. I love that feature of
Roon.