Local Template is a piece of Robot code located in suite files. It should be very high-level, hiding any implementation details into keywords in various Robot libraries (which in turn usually call even lower level Python keywords).
Some lower level keywords need explicit arguments and return values, as they can be called with different arguments within a single test, and the result values will be processed in parallel.
But that is almost never a case for the keywords called directly from Local Template. The values accessed by such keywords are usually stored in variables (scope Test or higher) of known names, and results are also stored in such variables. Therefore it is possible to not mention such variables in Local Template code, make it more readable.