ugh... most of the issues here would've been resolved had they not being retarded and actually communicated properly.
Instead of telling MC-kun properly that they are worried for his safety which is why they cannot allow him to continue being in the party, Sasha made it about the title and reward, made the other dude tell him he is unneeded and allowed rumors go around in the guild due to the nasty nature of the expulsion.
They gave him a safe job of item collection- but he felt like he isn't doing enough. Instead of communicating the importance of that, as he kept getting to danger, Sasha both didn't allow others to help carry the items, and she rejected the need for item collection (only the whatever item from the snake is important, leave all the other drops out), making the item carrying job more of a punishment then a necessity.
Moreover, the party itself didn't form around him being weak. Where should he stay during combat? Why did he move away from his position? What makes him think he can do stuff during combat against a super strong enemy?? His job is to provide items to the party, collect items from monsters, and hide so that he will not be in danger and risk the other party members.
He has a 'Master' skill, why kick him out instead of letting him SAFELY research his skill??
Not only that, but for a party that is just about an A-rank, to not know information about breeding grounds of some mega-super-duper strong monster, but know the type of flora that grows there...? the fuck is even that. And, the idea that once MC-kun is kicked out of an elite party, he ends up collecting leaves as if he doesn't have any experience of being an adventurer, any experience in his role in combat, and knowledge about items and tactics and locations and whatever... that just dumb. Other parties should try to recruit him simply based on the fact that he has a lot of knowledge and experience from that party.
This is dumb and I'm angry.