Many? Most? satellites going up these days are in close-to-polar orbits, so you’d like the rocket to launch near northward or near southward. So heading south out of Vandenburg is fine, but not out of Florida. Is it for practical purposes impossible to launch the rocket NEward or SEward but somehow get satellites into 80-deg inclination orbits? How about from Brownsville?
Yes you can do technically do it. The problem is that you don’t want spent stages or debris from a failure to land in populated areas. Going either north or south from Florida has this problem while going south from Vandenberg doesn’t [it is flying over the ocean]. You can do a dogleg maneuver from Florida where you fly east and then turn and fly north or south–but this consumes extra fuel.
Rare but doable. Space-X did it in 2020, which I believe was the first since 1969.