One of the many things I appreciate about Larian is that they don't do a lot of hand holding, but they greatly reward the curious-minded and they leave the information you need lying around. They leave books all around that explain various concepts - including Shar - you just have to take a moment to read them.
I reject the laziness of modern gamers that seem to require an endless amount of exposition. The standard of truly good writing is to show, rather than tell. In a twist of irony the books that litter the game would qualify as showing, as they are not delivered as dialogue per se but are part of the background history of this world.
If you do not have the patience for this game, designed as an intricately detailed RPG with a world full of clues, signs, stories, hints, and visual cues that tell you everything you need to know then I would invite you to go play retail WoW - Blizzard/Activision is more than happy - these days - to cater to the lowest common denominator of brain-dead player that wants an easy to walk, path polished, boring 'interactive experience'.
