You asked why, I answered why. If something is an issue for you, then feel free to offer alternatives or better feedback that could make it better, instead of counter-argumenting an answer you clearly asked for with even more questions. I even mentioned there is an alternative method that could address that, yet you conveniently ignored that part.

The main character is clearly the character created at the start of the game. Everyone else is an NPC because you cannot dismiss the main character, so what are you talking about by asking who is the main character. Clearly the character we start with, as all the story revolves around that character and they're the driving force that keeps pushing it forward.

Also I play the game as is intended; meaning singleplayer 4-man party with a main character and 3 companions, therefore my feedback is based solely upon that core gameplay experience exclusively. The proximity dialogue is a core issue that affects core gameplay, not imaginary what if scenarios. This is practically a bug with the game, which I'm addressing and offering feedback on how to fix and make better because it is not working as intended nor providing an optimal experience. In fact it detracts massively from the experience, as many others have had similar experiences.

So I do not worry about imaginary what-if scenarios for secondary optional aspects of the game such as custom companions, custom parties, custom modded parties, multiplayer nor anything of the sorts, because first of all this affects the core experience of the game, so these optional secondary aspects cannot get treatment until the core gameplay is fixed. And second of all because I don't play nor ever will play the game in ways that you mentioned.