You have to be careful with blanket statements like this. Southern Baptist churches are entirely self-run enterprises with no top-down doctrinal control from anyone else. Consequently, there are congregations who would qualify as high-control, culty organizations and there are congregations who welcome LGBTQ folks and such (although it's increasingly true that welcoming / progressive congregations are self-sorting into their own categories/groupings such as the Cooperative Baptist Fellowship).

I don't know of any SB churches that preach specifically that THEIR church is the One True Church, which is usually what that kind of control requires.

Certainly many folks in the SBC church of my youth moved from church to church, or even to other denominations, and nobody thought that was soul-risking behavior. A central tenet of MOST Baptist churches is the primacy of the adherent's personal relationship to the almighty, which is unknowable to others by default, so this tracks.