I suspect that many of us are uncomfortable with the choice of carrying Stidham as the player to count on if Brady were injured. Some fans just concede the season if Brady were to be injured; others prefer to have a backup that can bring us to the playoffs.
I preferred Hoyer as a backup that could take the team to the playoffs if Brady were out for a few games. I do NOT have the same confidence in Stidham; and no, one play is not determinative.
So, sure, let Stidham develop. However, bringing in a vet, for me, is a plus.