This is my problem with it as well. I used to have a self hosted nextcloud instance, but my main usage was for the file syncing. Nextcloud seems to be poor to decent at everything it does, but never great. So unless your goal is to have a suite of mediocre appliances that do the bare minimum, nextcloud is good. But all I wanted was a nice and quick way to sync all my files (I'm talking 500k files here) and have some sort of versioning in case I fuck up, so I moved to syncthing.
I moved from syncthing (and seafile) to nexcloud because I was missing one key thing: the ability to share files (by providing an URL, or to a group (think common files with spouse)).
I use Seafile and it has the feature to share to other users on your Seafile instance and to create a public link for uploaded files requiring no account. Is that what you're speaking about? I tried Nextcloud about a year ago, I spun up a Nextcloud and Seafile instance and Nextcloud was much slower for uploading and downloading files.
Syncthing is awesome for being a dropbox-like service for computers. I've setup a syncthing share as a folder inside of nextcloud which is enabled as "External Storage." This gives me the best of both worlds. Sharing between computers is rock solid. The mobile use cases is a lot more reasonable and I can share files.
I don't like syncthing on mobile because it needs to maintain its connection to sync and therefore drains battery. Also, there isn't a way to have less than 100% of a particular share local to the phone. This isn't usually waht I want on my phone.
Yes, it does work with Nextcloud - and this is the reason I moved to Nexcloud from Syncthing (and previously - Seafile).
I was just commenting on your migration to Syncthing, which is a superior syncing app IMHO. It is just that when I was using it I realized that I am missing the share ability, which is avalable in Nextcloud, though my (somehow unhappy) travel the other way round from Syncthing to Nextcloud.
I think that Nextcloud is trying to cover too much things, with half-baked apps.