In the early days it was cloud and mail, since Mailcow works really good, it's just the cloud. Because nextcloud is too much hassle, all this php stuff... I have a managed nextcloud at hetzner and I am really happy this is something I haven't to worry about.
I check ocis from time to time, if it is usable the same way, I would selfhost my cloud again. NC on selfhost? Only if they do the same steps ocis already made. Because ocis is a simple single binary without php.