The events of the Dragon Age novels and comics are “part of Dragon Age canon”, meaning they contribute to the overall lore. They do not, however, override your game choices. Those events hay have happened very differently in your particular game continuity… meaning that, if Alistair was dead, then the events of the Silent Grove simply never occurred. If Alistair isn’t king, the Silent Grove could have still happened… but would have occurred somewhat differently.
Does this mean the comics and novels could be referenced in your game? Possibly, but only if the context is correct… and, even then, we’d need to introduce characters and events on the assumption that you’ve never read the material. The Architect was introduced in Awakening assuming that the player never read the Calling, and needed to work as a new character. If you read the Calling, then great— you would have more insight into the game. It’s not designed to do more than that.
If someone really wants to assert that ancillary media cannot exist if it contradicts their personal playthrough in any fashion, then so be it. You’re not required to read it. You can play Dragon Age without ever picking up the novels or comics or whatever else. It will, however, still exist. If the knowledge that there is story material out there which explores aspects of the story you didn’t choose in your game (all of which are equally valid) bothers you, then you’ll simply have to take a breath and either pick it up or live with it.
And please stop with the crude language. You can dislike Alistair or Anora just fine without coming across as an inbred chimp. They are characters with very human flaws, and one can imagine many reasons to dislike them both… but your many feels do not make the rules of these forums irrelevant. Thanks.