Blue
Ravenous Bugblatter Beast of Traal
If I'm running Eberron, we have the Last War, and the history of the warforged, and the Dragonmarks and their Houses. I can run Eberron without Dragonmarked Houses just fine - but if I don't tell my players that and they are expecting them things will feel wonky and off.
So shared lore is important. It's both a shorthand between DM and players, but also a foundation that everyone is building on. Changing it can happen, but needs to be communicated.
One of the reasons I actively dislike FR - there's too much lore. I played a lot of it back in AD&D days, and the players that read every novel would know more about the world than I, and it was correct because the DM also did. There could be a plot going on and I would miss clues due to not knowing about how Sammaster fit into the Cult of the Dragon. Or of course now where I have lots of FR knowledge, some of which is years out of date because they've advanced the timeline, but other parts are still true which is even more confusing.
So shared lore is important. It's both a shorthand between DM and players, but also a foundation that everyone is building on. Changing it can happen, but needs to be communicated.
One of the reasons I actively dislike FR - there's too much lore. I played a lot of it back in AD&D days, and the players that read every novel would know more about the world than I, and it was correct because the DM also did. There could be a plot going on and I would miss clues due to not knowing about how Sammaster fit into the Cult of the Dragon. Or of course now where I have lots of FR knowledge, some of which is years out of date because they've advanced the timeline, but other parts are still true which is even more confusing.