Quote Originally Posted by Shurrikhan View Post
They don't, though. There are differences, for instance, between how BDO, Aion, B&S, Tera, and the like handled these verifications and the uptime costs, errors, or other artifacts that might come from it.
Re-read YoshiP's answer. He was comparing a single-player game where everything goes on your device vs an MMO where the information travels to the server and back and is checked.
Also, I like how you left out WoW, which has a much more reactive netcode despite being 10 years older than ARR.

Quote Originally Posted by Shurrikhan View Post
Having to verify the feasibility of an action that the client requests is pretty much universally important
Of course, it's important, no one is arguing about that. The problem is that SE's specific netcode introduces visible latency in the exchange between the client and the server, and therefore, when an attack lands, you may see yourself as outside of it and still inside of it server-side. And when you move, you are still standing still and casting for the server, hence slidecasting. That is a problem that is unique to FFXIV and most other MMOs handle it just fine.

Quote Originally Posted by Shurrikhan View Post
Just like various multiplayer shooter games have their different ways of handling such things, so do MMOs.
Shooters are a different beast, you cannot afford full server authority in an FPS because the generated latency would be too great. Which is why the client is given quite a bit of leeway, and that's how we get all the "wonderful" stuff that hackers and cheaters abuse.