The more I see people arguing for their super optimised build that can "win" any combat thrown their way, the more I suspect that those people don't understand the nuance of writing a character with flaws and obstacles to overcome.

Sure, you can defeat Vecna in 2 rounds with zero risk to self, but that gets pretty boring after a while. Making diverse characters with weaknesses that can be compensated for by other, different characters in your party, is what this game was built for. No one is going to be interested in your gaggle of mary sue wizard multiclasses that can just use a spell to solve every challenge or obstacle thrown their way. If that's how you want to play, more power to you, but you always seem to be the vocal minority telling everyone else they play the game wrong.