The only point of using warrants is to create a track that is more focused on flying and related technical specialties... as opposed to commissioned officers who are being developed to potentially become senior organizational managers, combat leaders, and ultimately strategists. The latter requires decades of marination, not just a masters degree and PME-I.
Could a warrant have done 1st Lt Mattis's job as a platoon leader? Sure. Would that warrant's career track have developed him to become CUSCC and SECDEF? No.