Infuse is terrific software, and supports jellyfin and smb. I use it for jellyfin and absolutely love my setup.
I ditched plex because of missing Dolby audio support and all the use hostile channels and “features” years ago, and will never look back.
For how much Infuse gets praised I was disappointed in the UI/UX. Playback is great, but the browsing UI is terrible and offline downloads are really buggy (Just like with Plex for a very long time)
Infuse is another $100 license to sync watch history, when I already paid $100 for Plex a while ago (with the primary driver being 'sync watch history', which is the basic feature Plex provides).
Paying more money to use a different product, and then expecting all of my users to do the same, is a big hill to climb.
So the Plex inertia remains.