Thing is, fine-tuned game balance is in most if not all ways greatly overrated as a design goal.there will always be some imbalance, but do we really need to throw any hope of somewhat balanced game right out the window with step 1 of character creation?
A flatter power curve and more emphasis on class abilities means stat balance becomes less relevant; along with acceptance of the simple fact that there'll be some characters simply better suited than others to a job or adventure or even entire campaign.
I'd even go a step further here and say the game itself should try to provide each stat roughly the same amount of work to do regardless of the campaign being run; not so much for "balance" reasons as to avoid there being an obvious baked-in dump stat like Charisma was in 1e or an obvious have-to-take-this stat. like Dex in 5e.in some campaigns high charisma will be more valuable than high intelligence or strength, but every campaign should be made with all scores being challenged somewhat equally.
I've run (and played in) many a game somewhat like that and have learned that each of those characters starts out with about the same average career-length* expectancy.you can try to make a game where half your party has 14,12,12,10,10,8 array and half 18,16,16,14,14,14 and over whole campaign say that both will have same effect in the gameplay.
* - I'd say life expectancy but some characters' careers end for reasons other than death.