The assignee field is similar to a linked record field in many ways: assignees are stored as special records in SmartSuite, with IDs and fields similar to normal records.
It would open up a world of possibilities if the Assignee field could be used like a linked record field in formulas, with access to the backlinks from wherever it is referenced (so you could write [Assignee].[Link to Another Table].[Field]).
For a use case take the situation where hourly rates for staff members may change. Centrally storing these rates in SmartSuite records would be very useful (because they can be amended in one place), but actually using the rates in calculations is hard. If we could write [Assignee].[Link to Staff Members].[Hourly Rate] in a formula it would make the database structure much simpler.
For another use case take the situation where a formula needs to know how many open tasks a user has. That's hard right now (you would need to centrally link tasks to one record with automations) but could be done via the assignee with
COUNTIF([Assignee].[Link to Tasks].[Status] != "Complete", [Assignee].[Link to Tasks].[Title])