Ease of setup was how I just got one techie friend and two non-techie gamer friends to set up Plex servers and we had libraries shared to each other within 15-30 minutes. I don’t want to think about explaining VPNs and SSL to them for the alternatives.
Plex still offers that option, it’s just buried in the settings.
i’m not sure why it would do this, i’ve never had any issues with watching plex while the internet is down (in fact that was one of my original uses for it, to have movies and tv in a building without internet). I don’t have it turned on but I do know you can go into server settings -> network and set a list of IPs/subnets that can access without any authorization at all. That lets you use plex without even having a plex account afaik.
As a techie I hate this answer but it’s hard to beat a Roku with Plex from an ease of use standpoint. My 70+ year old parents have no problem navigating it.
Plex has pretty bad DV “support” as an example. AFAIK it will only play back dolby vision profiles that have the HDR10 compatibility mode or whatever. Any time I get an older DV file I have to play it through some Android TV app.