I can live with this limitation for now (even though Nextcloud that we tested as well has it implemented)
With tags you can block users to access folders on various different rules.
If the have no access, the client simply wont sync - the subfolder(s) are then simply not present to these users.
But Seafile has a much better sync between Desktop and Server, that’s a big plus and Seafile can do fine grained folder permissions, which is also great.
Nevertheless, there is one topic with read-only folders that I think needs to be addressed.
https://forum.seafile.com/t/seafile-client-not-showing-warning-error-when-syncing-with-read-only-library-folder/8824/3