Actually those ranged champions who are abusing Conqueror are all mages, as far as I'm concerned.
As I see, it is abused more by mages than adcs because ranged abilities still gain 2 stacks.
The nerf will make Conqueror not viable to adcs, who don't abuse it.
So I feel that the correct nerf direction is making ranged champion skills only stack 1 too.
Or, actually, Riot is just having the concept that Conqueror is inherenetly a melee-only keystone?