The unfortunate part is that CoreELEC only works when you get all your content from a locally attached disk. You can't even really stream it from your beefy NAS/server, and you definitely can't use any streaming services.

I'm constantly surprised how many people are in that narrow category of just dipping thier toe in the water for "self-hosted" content that it's little enough it fits on disk storage you can have in your living room (mine is a half-height server rack in the basement), but also have progressed past thr point of using any streaming services. I guess there are a lot of people without families that also never travel out there.

I used it with plex (in kodi) just fine. With that said, I'd agree that its mostly for local media (where local can be whatever plex can get to). Outside of plex, either you are using plain kodi or some simple kodi extensions (say youtube) that just aren't as nice to use as their android app equivalents (in regards to streaming services, it does support MLB.TV for those that like baseball, but again, not quite as nice an experience IMO as the android app).