Yes, with NPT (National Pipe Thread), both male and female threads are tapered so they tighten as they screw together and there is lots of contact between the threads for good sealing and mechanical strength. On running threads, you get a good fit if the threads are a nice tight tolerance but that rarely happens on generic threaded parts. Any dings can make them hard to screw together. They also never get tight unless they bottom out or tighten against a stationary surface. A tapered thread screwing into a running thread will tighten, but you only get a good seal on a few of the threads that start to get shallow towards the back of the threading. It puts a lot of stress on those threads.
Except for the Automag in front, its usually the man behind the equipment that counts.