One way to understand the Federal Vision controversy is this:

Once there were natural, intellectually satisfying, historically grounded, and Biblical reasons for a Calvinist to not be a baptist.

Now there are only fallacious reasons for a Calvinist to not be a Baptist because the traditional reasonale is declared to be virtually “Roman Catholic.” (One must choose between Rome and Geneva even though this means consigning Calvin’s Geneva to Rome.)
The new view really can’t stand to allow the traditional view to be in the same room.  The emperor shies away from mirrors.

The problem is that the Westminster Assembly allowed peaceful co-existence, but their newer children want to purify the family in the name of the Westminster Assembly.