What is the benefit of not allowing it?
- Players get the experience with the NPC's, as intended at launch.
- They haven't worked out how it works with flags and progression witth four Tavs, and now they dont have to.
- Players with four Tavs will miss out on a truckload of content and complain about it.
- They can keep it in reserve for Icewind Dale 3
- The game could be massively unbalanced with a highly optimized party of four and cannot be tested at launch
- They can gather metrics on bugs and quest-related issues without having to account for four Tavs
- They have narrative reasons for it; ie. Where do the Tavs come from?
