I have he same problem and I also find it non sense.
It can't be serious that I should have to select and follow each of my colleagues and vice versa
just to send them a link to a content.
Then at least an invitation with external email should be possible.
All of the dangerous features are implemented like facebook and all the stuff which is prohibited in our company, but a communication inside the scn network between users is not possible and unsecure?
I'm surprised and disappointed.
This is non social and no network, it's more an isolation.
:-(