@Eksentrysyti No, there are a game where you can build a broken character like that, usually an older game, I play a lot of that kind of game in the past.
I used to build a broken 2nd character like him, assassin with full agi, I can't kill anything but the lowest level mobs, but in return nothing can hit me, not even archer player with full dex. I often pulling aggro of an entire maps just for giggle, trolling people by delivering a train of monster, fighting against tank with no dex in pvp. Why did i do it? because it's a game, i'll do it because it's fun. And that what the MC problem, he still thinking that this is all just a game. That's way he keep smiling and laughing, even when he face a real danger of being killed by a stun-lock slime, he is still laughing and smiling, because its just a game, nothing bad happen in the game.
If the author want to make this story a great story, he should make the MC doing something really stupid and be responsible for the death of his friend and realizing that he is not living inside a game but a real world where death is permanent. Thought i doubt it the author have enough brain cell to write something like that, but who knows?
Sorry for my bad english.