Game balance is about the core mechanics in the game, and how they're balanced with all aspect of the game.
Just quoting what is pertinent to my reply.
This is the gist of it, isn’t it?
It’s easy to say to not to choose cheese options in the game but when the developers expect you to use them, it’s a problem. Goblins almost always rush to high ground. There’s explosive barrels and special arrows everywhere. Larian expects you to use those homebrew mechanics.
It’s the reason why at the grove you have a huge height advantage against the raiders. It why they decided to put barrels in strategic locations. It’s why you can jump and attack with advantage from behind with minimal cost.
You literally have to hamstring yourself to attempt to play this game using 5e rules. If players have to police themselves to maintain some form of balance in the game, that’s not player options. That’s just bad game design.