English uses the reflexive form when both the actor and the recipient of the benefit of the action are the same person:
Mary helps advance John's career by talking to the president of the company: Mary did him a real favor by talking to the president.
John advances his own career by talking to the president of the company: John did himself a real favor by talking to the president.
The technology company did not describe the technician in terms that really reflected his wonderful abilities: The company did not do you justice when they described you as "competent", you are really amazing!
The technician did not describe himself in terms that reflected his wonderful abilities: You did not do yourself justice when you described yourself as "competent"; you are actually much better than that!