It's not always the default.

By choice on big power stuff I would use an external waste gate with a soft spring using the air injector to pump air onto the gate to keep it closed. This way if the injector fails it returns to spring pressure, which is soft.

It's one of the reasons I used an aftermarket controller, but in my scenario I will run the turbo flat out so I wouldn't notice if the gate stayed shut anyway

so in the smaller turbo aplications they are run near flat out anyway so the fuelling is generally safe without boost control at high rpm as we are demanding the gate is closed up there anyway