Such letters would also be needed in a "structured " church as the one I belong to.If I were to relocate or just decide to change churches locally,a similar procedure would occur...however I would have to look in the manual to se if the church board was brought into the picture. I think (by my poor memory) that because the Pastor is under a superintendent and serves at his will along with the local church..that he is the sole voice needed for a reference.Without it there could be no membership transfer at all. I am not sure what would happen to the person..perhaps a time of attendance and them membership classes there if that Pastor decided.
In my denomination the pastor is the decision maker..
Baptist's pure democracy is both a blessing and a curse. On one side, that democracy decentralizes power and helps to eliminate those who would "lord it over the flock". At the same time, that democracy can lead to some very strange things (As a prespected former pastor of mine once said, "The majority is never right!").
With that said, however, I recognize that the recent resurgence of conservatism within the SBC only occurred as a result of that democratic structure. If the previous "heirarchy" had held the type of power that your pastor does, then things would have never been changed.