Adding sharing a single file by selecting users will cause some inconsistency:
The syncing client and drive client can’t display the shared files
Enable sharing single files to users will make people to think about sharing single files to groups. But if files can be shared to groups, people will see files at the group page (top level). They will also think they can create files and upload files to the group page, which is not possible because there is no library to store these files.
I think it is better to use sharing links for share single files. In a future version, we will add the feature to make files shared by sharing link editable.
I think if this works, it’s okay. Then you can post the links into chats of the groups. Maybe you’re right with your arguments, but aren’t shared folders marked as readonly today. And under favorites single files can apply.
This option will not work on syncing client and drive client, as you mentionned it.
But editng the shared files will be possible , which is the main lacking feature
Implementing single files sharing is difficult due to the multiple contexts (Clients, Groups, etc.)
These context issues could be adressed by means of restructuring the UI on web and clients.
I understand your arguments, but i think this could also be improved in the future.
For exemple, i posted these feature requests several month ago (not really related…)