Right. See? That's kinda my point. The companions at camp are just sitting around doing nothing all day currently. They're perfectly fine with you never putting them in the party. Wyll's just fine with you not putting him in the party to go get Spike and jazz. Lae'zel is fine with you never finding the creche. Etc. etc. etc. Meanwhile, they're doing absolutely nothing.
This idea, at least, gives them some use at camp. Heck, maybe they can even implement an auto-useless-item selling mechanic where you leave all the useless crap you find during your adventuring in the camp storage, and during the day while you go adventure, the party members you leave at camp auto-sell the useless junk that's only worth like maybe 1 gp, for you so you don't have to micromanage all that crap. Kinda like, "Whatever you put in this storage box at camp, we will sell for you at the Druid's Grove while you're gone."
So they take care of food management, useless item nonsense like forks and knives and spoons, repairing weapons and equipment, etc. while you and 3 others (or 5 others) travel around risking your life and such.
And yeah! It would be awesome if Larian did something like have Lae'zel decide to venture out alone during the day after x number of days of being left at the camp. She gets restless and heads off to find her creche herself. You're not giving this questline enough attention, so she's going to take matters into her own hands. Then maybe she gets into some sort of trouble and is trapped in some cave or something with gnolls trying to eat her face off. You and your party members hear about it from either one of the Tieflings or another party member you left at camp. Better go save Lae'zel before she's eaten!
I also like the idea of solo side quests, like the mention of playing Astarion prowling out on his own searching for prey. You left him at camp too many days in a row, and he's bored. So he's going out hunting. Maybe you even have the option of getting him into trouble. You can choose to either hunt animals or goblins - or hunt a few Tieflings who have wandered too far outside of the Grove. If you get caught, and Astarion loses the fight and/or is unable to flee, he is captured and thrown into a cell. Someone reports this to the MC, and now you, the player, have to get him out of the mess he's in.
Same with Wyll. Maybe he gets antsy because you left him at camp too many days. So he sets out to find Spike on his own. He gets captured, you have to save him. Or maybe, you play the part well enough that you succeed. Kudos to you, player. You did a tough solo quest and won.
Whatever. The main point of it all is actually to provide more importance to so many game mechanics that, as of right now, have no importance. You have gobs of food that never go bad and are truly meaningless. You pick up tons of weapons that, again, are meaningless except to sell them. You leave characters at camp who meaninglessly do nothing the entire time you're gone. They don't craft, cook, clean, maintain weapons...nothing. They're just there, picking their noses and scratching their bums while they wait for you.
And, again, I'm all about story and the story making sense. It makes absolutely no sense, right now, why 4 party members is "Full Up". None. What? I can't travel with 5? It has to be 4? I might need a 5th party member, or 6th, especially facing a giant deadly spider in her lair, but nope! Can't. Why? No reason. Just 4 is the max you can have in a party. It'd be better if the characters never say anything about you being full up than to say that you are full up and so they can't join you. At least in other games, it is just part of the game mechanic and nobody addresses it at all. Because your characters in BG3 address your party size, it is emphasized and makes it even more stupid. If you are going to have the characters say that you have a full party at 4 characters, then give me a good reason WHY it is full up at 4. Don't just say, "You're full up." See. Me, the player, I'm immediately sitting there thinking, "Why am I full up? What's 1 more party member in my party gonna hurt? Why CAN'T I have 5 or 6 at least? I mean, maybe more than 6 might be too large a group and all for stealth missions, but if I'm going in guns blazing, I'm gonna want an army. I'm gonna want as many in my party as I can take."
Anyway, again, it's really a minor thing. I just thought it would enhance the game.