I start by fully admitting I hate characters that are uber optimized. Yes everyone is allowed to play any way they want, but I dislike when players do pure character optimization for combat. I find it very one dimensional and it turns DnD for a ROLE Playing Game to a combat board game. If that is how you want to play then just go buy a bunch of WH40K minis and play a pure math and combat game.
This brings me to my question. How do you balance your campaign? If your campaign is just a massive dungeon crawl then being 100% combat is the way to go, but a role play game should have balance. So how should a standard game be balanced? 50% combat 50% social interaction? Do you favor one over the other?
How much social do you think a campaign needs so that players who make balanced characters are happy and pure combat monsters are gimped enough to feel like they shoehorned their character by their choices?
I reject your premise... "but a role play game should have balance."
If you are choosing to run a mega-fungeon crawl (sterrotype) you are running a style of game that does **not** need to balance and may be ideal at 70% combat, 25% explore and 5% social.
The balance between these three pillars (and others) is a style of game defining element and should very accordingly.
In a large numbers gsme, say 6+ players, I find it's got a LOT of table side pressure that leads to focus on group scenes over solo scenes (pushing back even duo scenes) so those tend to get more combat focus than social since those types skew the numbers gsme.)
At 3 players, I tend to go more social but at 5 players I tend more action.
Then you bring in players likes and dislikes, etc.
I expect my 5 player game starting next week to be more along the lines of 50% combat, 30% explore and 20% social after all those factors are involved... however... it's really comes down to the characters choices.
I tend to plan for two different pillars to have "solution" possible paths for the challenges. Often a third exists too but I dont make an effort to put three. Often the third pillar helps the other two.
So, it's up to the PCs to look for, find and choose the options they want.
That leaves the final "balance in their hands.