Each to his own but the cost of a bottle and associated equipment, cost of refills, regular checks to bottle, transport of bottle and insurance risks, refling air cylinder on rifle are negative issues to me. As I said, carrying a 50 round box of .22 subs swung it for me and 15mm groups at 75 meters is well acceptable accuracy for me.
Admittedly, the downside can be shooting near buildings or restricted areas in which case, yes an FAC air rifle is preferable in the interests of safety !