I can understand what you're saying Punks as its not that different to a kimberwick or a pelham ridden with a 'D' rather than two reins without a curb chain
I've seen people in the UK use them like that as you get some poll pressure and more control than a plain or straight snaffle but not as much leverage pressure as you get with a curb chain
It could be argued that the port makes them harsher but I've known horses to be happier in a ported bit than they are in the nutcracker action of a jointed snaffle
Yes Exactly!! It's like using a kimberwick or a pelham without the chain! It adds a tiny amount of poll pressure, just enough to help give the horse the idea to break at the poll.
I'm not sure though how a ported or mullen mouth bit is harsher than a jointed bit? Maybe stronger than a french link? I'm not sure?