Why? Because you are depending on a third-party program to generate precise data that would otherwise be out of your control. Don't give me the "it's part of the game's coding" ********. You are influencing the game's coding, much like an Action Replay.
Generating a hypothetical tool-assisted shiny with 31 IVs with all stats in about an hour or two by abusing the number generator is not an accomplishment nor requires any effort compared those results achieved via normal IV breeding.
Try spending months breeding a perfect pokemon without any tool-assisted programs and then tell me it's still "legit"
Are RNG'd Pokemon Hacks?
No. They are completely legitimate Pokemon, as opposed to Pokemon generated with an active Action Replay.
People really need to learn definitions of things rather than calling things by what they think they may be.
Legal=/=Legit
Legit and legal are two very misconstrued words here on the forums. Legit and legal are really bad words. "Legal" hacks are still hacks, legitimate hacks are hacks, and there are no Legal non hacks.
External Device=/=Peripheral
Peripherals attach, were not sold with the system. EDs have no physical influence on the system.
AR=Peripheral
Computer=External Device
Any electronic peripheral that comes into physical contact with your DS eliminates legitimacy if used at any time while connected/running. Legitimate Pokemon must be obtained in game.