I'm not gonna deny that there are definitely lots of Plex fanboys, but there are also definitely a number of issues that legitimately makes it hard to switch.
For example right now, I can cast from Plex to my Chromecast. In Jellyfin, the cast menu just shows "Play on my device". Afaik the only alternate app that also supports Chromecast is streamyfin, which seems to be in beta because the cast menu shows icons for my Chromecasts but no name and won't let me select them.
It's recessed with a rubber plug with an added o-ring. That's more protection than the barrel jack on my e-bike has.