It doesn't matter if I'm using a bow, or a sniper rifle, if I have high ground, I'll have an advantage, double that if I have cover. Your net benefit is also wrong. You don't have a +10 to hit because you have high ground, you have the advantage roll, + any bonuses you may have, and minus any penalties, are you human, shooting into a darker zone? The penalty to your opponent does not affect your hit chance. Being higher does, because, as in the example laid out in the post I replied to, you can shoot over that cover, whether that's another NPC, or a boulder, or a barricade. There's a reason snipers go for high ground today. I don't really want to go into the full physics of projectiles here, but we'll suffice it to say that arrows or bullets do not climb higher as they fly farther, but drop, and that drop can be significant, according to the range, and the initial velocity of the projectile.
Wrong, for a host of reasons.
1. Not bringing in IRL flight patterns of objects.
2. The "net benefit" is different from a +10 to-hit. A flat +10 to-hit would actually be less impactful because then the lower attacker wouldn't suffer as badly. This is just bad faith arguing on your part.
3. You're...making my point? Elevation changes should be beneficial, just not as stupidly game breaking as they are now where there is a functional equivalent of +-10 to the to-hit rolls between them (it's actually more than that because the chances of a Crit and a National 1 are doubled respectively). Implementing cover rules per the rules of 5e drops that number to +-4, and significantly, also makes less impact on various Class Abilities like Rogue Sneak Attack and others that rely on advantage/disadvantage. It also means that having the height advantage isn't *always* a benefit or a detriment, depending on the lay out or how you play.
Actually, let's revisit #1. Snipers go for high'ish ground, not the highest ground. Because you don't want to silhouette yourself against the sky/backdrop. Snipers are trained to go for the location with the best ingress/egress, best sightlines, and best cover and/or concealment. This may be the highest ground, this may not be. They don't do it to increase the range of their rifle, they don't do it because it makes the rifle any more or less accurate. A properly doped up rifle and sight makes changes in elevation practically irrelevant in terms of hitting your intended target at ranges. Doubly so if you have some of the newer sights and laser rangefinders that account for elevation/windage when you're sighting-in. I went to school for it, I'm pretty well versed.
Lastly, and this is why I wanted to revisit it as you clearly don't know what you're talking about, bullets absolutely do 'climb' as they fly further. Unless you have the most insanely stupid sighting-in for a rifle, bullets will leave the rifle and achieve a higher elevation during their flight than their point of origin. This is to compensate for the impact of wind resistance and gravity on bullet flight path and the minimal difference in point of aim versus point of impact at most ranges. But if your rifle is dialed in for 300m and you aim at the head of a target only 50m away, chances are pretty good you'll miss because the bullet flight path will go over the target (caliber dependent). This is a simplistic discussion but it gets the point across ->
https://www.hornady.com/team-hornady/ballistic-calculators/ballistic-resources/external-ballistics
