The main advantage is more-longer-stem selection.
You really can't find 140-150 mm(reach) quill stems
The stem clamps on the threaded stem very firmly. Doesn't really crush the threads much either( probably crushes them fairly uniformly, but not deeply).The stem is a tight fit on the threaded steerer-actually I sorta' thread-twist- it on.
It is a very nice for for $25- nice ride.
I'll invest $4 in a star nut and try it.
Thanks
Charlie