To be fair changing your FOV isin't technically part of the game, if you go into the game settings there is no option for you to change FOV you have to manually go into in game files to change it.
Addressing the comparison between game bugs and things that are "part of the game", things that are part of the game can also be a bug, for example quick peaking is in some instances abused to where you can't see the player quick peaking you because they peek too fast, is that a skill or is that cheating? It seems to me that there are multiple things in the game that are abused, but we only care about a few of them. Another example like looking through rocks and looking through walls, everyone knows people are looking through rocks and walls but no one really cares or reports it unless you see somebody actively "backpacking", and even then everybody does it.
Also jumping into an infrit will cancel the animation of you getting into the infrit, jumping over an infrit can bug the game to where your character will be shielded by the infrit as you're jumping through the infrit making you invinsible for a second.
My point is that if we are going to ignore many bugs that are abused and that you don't get banned for, why don't we allow DPI jumping with rules preventing it from being abused.