Thats because they are a true 50 ohm connector and have the ability to be attached without multiple turns of a test probe lead or other cable. They are ok for stationary type, semi permanent useage but even then can be sketchy. BNC use on a portable radio is a poor choice as every wobble and flexing of the antenna contributes to it's loosening by physically stretching the outside securing ring. They are also virtually impossible to waterproof and have poor physical strength overall compared to the newer types of connectors used on most every portable these days.