Multiple employees associated with one user?

As a new participant I would first like to congratulate the community with maintaining this wonderful project. I have been developing in OpenERP and Odoo for a good number of years but would like to return to the open source spirit which initially drew me to OpenERP. Using Tryton feels like switching from Windows to Linux. Liberating!
I am looking forward to working with the community to make Tryton even better.
One thing I noted during my initial explorations (while trying to make a case for a client to migrate to Tryton from an old OpenERP system) is that Tryton allows several employees to be associated with one user. I wonder what the use case would be for this feature? I hope somebody can enlighten me.

This allow a user to surrogate employees that may not have access to the system.
For example a secretary that is filled time-sheet for workers.

Also in a multi-company environment a user may be an employee of each company.