I run as a rogue, although I would have preferred to play a ranger, but I knew of the 4 party limit, so I figured that a rogue will come in handier. I was not aware that you can have sort of hybrids that can act in other ways. This is cool. But we can face the obvious truth, only a small minority knows enough to exploit all or even most of the possibilities. Larian in BG3 is also particularly bad at communicating to the player what is possible, while also giving you the standard composition right from the start. So the vast majority will just choose the way of the least resistance and effectively be locked out of a large portion of the game.
This does include party banter and interaction, but also a lot of synergy and gameplay interactions. So your mage/ranger can unlock most doors? A bard can fill multiple roles, as spellcaster, supporter or damage dealer? You can have multiple actions in one turn or totally substitute certain primary roles with clever skilling and leveling or the heavy use of consumables and resources that are yet unclear and complicated to handle/refill? Cool, I had no idea and that is why I solely use my fighter, rogue, mage, cleric combo, because I do not know enough as I am not told and shown enough.

So, as a casual dude, I am pretty limited in my playstyle. Giving me another character to dabble with would allow me to discover more synergies by myself or play doubled roles differently.