Oh I know all of that. What I am talking about is actually being able to direct a spell at what ammounts to a speck on the horizon from the deck of a ship where actually keeping that speck in sight is a problem. You all know how much the rolling of a ship and the waves in between (although in a crow's nest the waves really aren't a problem when blocking LOS) can obscure a target and make it difficult to keep a bead on. And if you are looking through a scope or telecope or binoculars, it is that much worse because of your field of vision being SO focussed.
To me it just makes sense. Casting a spell at someone who is at the extreme range of your vision is going to be harder than casting it on someone a block away. For example say you're out in the mountian and you see a guy up on a hill about a mile and a half away. You have no scope, but since you can technically see him, you can hit him with a spell, so you cast your spell. Now imagine what you are REALLY seeing is an interestingly shaped tree, or a scarecrow, or a drone. Sure, you can still cast at it and the TN goes way up, but if you could see it clearly in the first place, you never would have cast the spell. I'm just syaing distance should be considered.
Gabriel