in my view, companions can never be the protagonist, because the companions are not the player character, they are npcs.
I totally agree with the principle of this idea and believe it is how things should be in a BG game.
t
he companions might have their own legends, but they don't have the destiny, and even they are not a candidate of the destiny.
The inherent issue is, unlike previous BG games where our PC was very much the protagonist/"special one" with a supporting cast, in BG3 all the companions share the tadpole...thus creating a situation where every companion shares in the 'special one' status...because of Larian's Origins system. The main protagonist status no longer belongs to our PC alone, it is now shared amongst this ensemble of companions that are also playable. Every companion just seemed to overshadow my own character and I found it hard to create any enthusiasm like I did in previous games.