Prime Requisites, or Ability Scores are not important

"In the OSR, ability scores are not important. They are deliberately so because it would be bad design to put too much weight on attributes you roll randomly"

This is something I read a lot on the internet, when skimming blogs and forums up and down, reading things about my favorite games. And I want to make an argument against it, because it's not really true.

They are not big in protagonismt on OD&D's "mechanical" side. Their uses on proper gameplay are but hinted; a numerical descriptor of the character so you can imagine it better, and for the GM to be used as he sees fit. But they are decisive on a crucial part: the prime requirements. 

A correct ability score can allow or veto a class. Not only that, it can put two characters of the same class at disadvantage, by allowing one to advance faster than the other: having the correct score on the correct ability allows you to progress a % faster . It's not like its a dealbreaker, but if you think about it, what's the point on it?

I guess its because it felt genre appropiate: You want to incentivize strong fighters in your game. You want to incentivize intelligent wizards. But if that is the reason, it feels like the lamest way to push that. If your low STR fighter cannot hit hard in melee and relies more on the bow, it's not too bad. But that the same low STR fighter receives less XP its a dissociated mechanic. It doesn't exist to reinforce the world or a reality, it is just an empty punishment. 

It's not really 3d6 in order if you must reduce attributes with that point buy, and get the appropiate one (providing that you can pay the amount of attributes in a 2:1 proportion) just to not play a gimped character. 

If its for being genre appropiate, I can think on much better ways. For example, allowing one re-roll, and just telling fighters that strength will help them performing their class role (even if its by a small +1 to hit). 

The ability score could also be dismissed, and, if its something needed by the class, just implement it in the class. For example, in the case of strength again, just get rid of it. Then declare "being strong" as a fighter base ability. Yes, I know its sounds so bad, but I am assuming you need strong fighters because genre fidelity.

Another method is what I am doing at the moment: I don't do XP increases for anyone: the prime attribute must be useful by itself, or not exist. Strength already powers up your attacks, so it is a good thing to have by itself. So, I allow characters to increase their prime requisites during the game: every level up, roll 1d20: if you roll equal or over your desired prime requisite, you can raise it by +1. 

This makes fighters a little more strong, mages a little more intelligent, hobbits a little more dexterous. I could probably extend this to any chosen ability instead of choosing the prime requisite, but as the specific abilities are what help the characters to fill their class roles, they would naturally gravitate towards STR, INT and DEX, probably.

Instead of using requisites as a dissociated punishment, I use them as an associated reward (that still creates the genre appropiate tropes). I feel that its also nicer for a fighter to feel he might get that precious +1 someday than to accept that it is gone from his hands in the very moment the character is created.

But enough with prime requisites, I want to go further. In OD&D at least the scores were not so important beyond that. I cannot talk about AD&D because I am not familiar with it. But B/X's strength modifiers are TERRIFYING

When talking about damage output in D&D, a +1 to damage is roughly equal in power to a +2 to hit. This means that every strength modifier you get, your fighter is getting a +3 to hit. 
And this means that a level 1 fighter with +1 strenght is attacking as a fighter as high as 8 levels higher than him.

It's not that its bad, but it is certainly a lot for a game in which ability scores do not really matter.

Imagine being that special guy who rolls a +2 or a +3. 

Constitution can also be a very desequilibrating attribute, but also Dexterity with the AC and Missile fire adjustments. Both are great examples on how a great roll or a couple of them can put your character several levels above their capabilities. 

Wisdom, Intelligence and Charisma are not as decisive, I guess, though it can be because I dont usually feature much hirelings in my games and players do not seem to care about getting more than one or two, though I can see how a maxed out charisma can be exploited through encounter checks. There is not much more to add but for encouraging you, dear reader: should you be thinking on implementing a houserule (such as relying on "roll under" ability checks for something) and the idea of putting too much weight on the scores is holding you back, don't hold. They are already heavier than they look.