And what happens if the GM miscalculates and defeats the min-maxer? That's a TPK. Or what if the one optimizer acts differently than expected?
You're breaking this down into somehow a plan will execute perfectly, but that's just not happening outside of some theoretical white room with theoretical players that do everything as expected, and dice don't have good or bad streaks of luck.
The simple truth of the matter is that this is a problem multiple GMs have encountered, irregardless of system, throughout the history of TT gaming. Trying to trivialize the problem, as if the GM isn't doing their "job" (which in this case does take time and planning in a very busy world that isn't so generous with such free time) is just ignoring the fact of the problems existence.
Good day.
Please, Read the whole entry not just the first sentence before judging a post. I addressed that in the very next sentence.
"The GM makes the groups sends the groups into battle and chooses who they attack. There is no reason for a more powerful fighter not to have a reputation that causes the boss/champion of the group of NPCs to head striate for your min/maxer player (if he kills your min/maxer he leaves considering the rest of the group not worth his time and leaving the minions to fight a square fight)." ... continued with other examples....
The problem is largely the GM. You can't blame the players or luck (good/bad). I listed multiple ways to deal with that not just one. On top of that what if the min/maxer is defeated? As GM you could capture the squad instead of killing them all. PHB p198 (PDF p182)
K n o c k i n g a C r e a t u r e O u t
Sometimes an attacker wants to incapacitate a foe,
rather than deal a killing blow. When an attacker
reduces a creature to 0 hit points with a melee attack,
the attacker can knock the creature out. The attacker
can make this choice the instant the damage is dealt.
The creature falls unconscious and is stable.
If your TPKing the group as a GM, you made the choice to do that. Your choice most likely sounded like "I am going to pit this group vs a hard challenge I think they can beat but I am going to let the dice fall where they may and if its a TPK its a TPK. That way they know the threat is real." So you basically chose to leave it to luck and you chose to do it with a group that could potentially kill them. If that is the case then you as the GM killed the group. Now if you gave them fair warning. Let them know this is fight they could TPK on and gave them another option to stall the fight until they were more powerful but they chose to go now... Then sure its down to the players and luck. ... but if you didn't and you provided no way out but death or victory... its on you as GM. Being defeated can be part of a story. A GM TPKing a group because he doesn't want to put in the effort to give them a chance out or who has decided that the players are running the game even though the GM made the story, built the encounters, built the world, told them everything they needed to know to make decisions, but "thats just how the dice fell"... is at fault.
I am not saying you don't ever allow a TPK.... but that is exactly it... you have to allow a TPK it doesn't ever happen without the GMs consent.
Players need to know if your that kind of GM. If they do and they agree to it that is fine. However, if you are... don't blame them for wanting to min/max... your creating the environment where you are punishing players who didn't. Then getting upset and complaining about "group balance" for doing it!?!?!