Originally Posted by etonbears
I didn't engage with the specifics of the DnD player's argument ( the mathematics of the 5e system ), because I don't play TT and, therefore, really don't care. From the viewpoint of a video game player ( which is what I am ) the core design of BG3 is the environmental design, the controls and actions available, and how the game plays, regardless of how these are realised.

The game, as advertised, includes a strong vertical emphasis, gaining obvious benefit/drawbacks from difference in height, and similarly gaining obvious benefit from attacking from behind - which is possible , seemingly, because 5e is turn-based, but has no facing, ZOC or positioning rules.

Okay, but this makes no argument for ADVANTAGE due to high ground. Why isn't the height itself, and thus larger ranged attack range a sufficient bonus? You're also harder to hit when you have the high ground because enemies on the low ground have reduced range. You can also sometimes destroy ladders behind you, making you unreachable by melee combatants.
Originally Posted by etonbears
Obtaining these height/backstab benefits is not cost-free, as you have to move into position, and movement is also a resource. The positioning benefits also apply equally to all actors, and the benefits can be lost/negated by opponent movement, so considering your movement becomes, relatively, more important.

This is incorrect. There is basically no cost to moving to high ground: you simply walk up some stairs/a ladder. This is even more true for backstabbing, simply circle around an enemy. I would agree with this point IF you could choose between taking 2 actions or a move and an action. Then you'd be choosing between gaining height OR getting 2 attacks.
But currently, it's often cost-free to move to high ground/circle behind an opponent, since you wouldn't use that movement for anything else. The only scenario that has costs is when you're running away from an opponent and could provoke an AoO or use your bonus action to jump.
Originally Posted by etonbears
This is unlike the dozens of feats/abilities/spells mentioned that presumably will continue to pertain regardless of how actors position themselves, and are therefore tactically superior to gaining positioning benefits. As the resources used are trivially restored between encounters, at the press of a button, those other mechanisms are effectively unlimited in use.

Again, no. Many feats/spells/abilities are invalidated by height/backstab advantage. And you have it backwards: many of these abilities COST AN ACTION, and thus are almost always tactically inferior to the (again, often cost-free) decision to walk up a hill. You say that height/backstab involves cost benefit while spells/abilities/feats do not: this is the exact opposite of the current state of the game.

Originally Posted by etonbears
Larian ( with this and the universal bonus actions ) are clearly of a mind that when you actually get a turn, all characters should have variety things they can do, not just attempt to hit the nearest opponent, and in all likelihood miss. You may like playing 5e TT, but it has been so over-simplified that RAW would make an exceedingly dull video game by the standards of the bulk of videogamers.

I literally suggested to replace height/backstab with a +4 bonus instead of advantage. This would COMPLICATE the game, by adding lots of little bonuses that could stack. The game would be much improved to its current state if backstabbing and height gave numerical bonuses instead of advantage/disadvantage.

Honestly, I think you read the first line of my post, where I disagreed with you, and nothing else...