The only reason is that you need to have a platform every 5 feet or so.
Nobody is saying you can't take a drone out, they're saying you can't use SAMs from 30 miles away (affordably, I'm not made of money, unless I'm the DoD) so you need a ton more platforms.
Lol, the issue is speed. By the time that barrel moves 10 degrees left, the drone has already circled it 5 times before smashing itself into the engine compartment and detonating the attached device.
Oh, you mean long range? You ever try to shoot buckshot at targets 300m away?
Drones used in war aren't quite here yet, but they will be. The only way to defeat this is to sever the connection.