Our natural gas suppliers used plug valves on the gas lines -- they have started to use some ball valves, but still have many plug valves -- we used plug valves on gas valves on the boiler (many are still hand operated) -- I assume they were used for a) ¼ turn, easy to operate, b) full bore, small dp, c) squirt of grease now and then kept them working and sealing, minimum maintenance, few parts...