@Wynne: your arguments would be valuable if we knew anything about the plot in BG3. But here, they are only speculations as to why we have to commit. It doesn't matter whether there will be 3, 4, 5 or 6 companions we can choose to accompany us further. Because maybe we don't even choose at all by picking the ones we like but more like they follow us as a consequence of what we did and what they did in the first act. So let's see how it unfolds in EA before writing books about it, shall we?