Agreed. Are DMs dictators? Or do they rule with consent? Tables vary.
For me, when I DM I let the players roll their new hit die when they level up, and after seeing what they roll they can either keep that roll or take the set flat amount. I'm aware that it prevents low rolls but still allows high rolls; that's why I do it. Low hit points are a much bigger disadvantage than high hit points are an advantage.
When I read your story (wife rolling low, friend rolling high, no-one happy) my first thought was that if I was the DM I would have every player roll stats (using whatever method I favoured at that time in my gaming career), and after seeing what they rolled, each player had the option of discarding the whole rolled array and use point-buy instead. Like the hit point example, it allows high but guards against low, and I'm cool with that.
There could still be a discrepancy between arrays, but it is mitigated by the fact that you can (to use your words) 'have whatever you want' anyway, so everyone is happy. Or at least, less unhappy.
How would your story have differed if that DM had done the same: allow you to discard your rolls and use point-buy? Would you be happy that you can 'play whatever concept you want', or would you still have been unhappy that other players had better arrays than you because they rolled them?
Would you have rolled an array at all (knowing that you could switch those rolls for point-buy after rolling), or would you refuse to roll and just use point-buy?