Is there a difference between someone that is 5'8" and 5'9"? Sure. If they're standing side by side you'll notice. On the other hand, just looking at someone like my friend from college that was 4'8" (maybe) and someone who is close to 7' tall do you notice a difference immediately? I think most people will.
Intelligence scores, like IQ scores are just a measure of relative intelligence. An ogre has an intelligence of 5 with limited vocabulary but still functional. That to me, sets the bottom bar for normal human intelligence. A 20 is as high as a mortal can go in D&D without magic. The "difference between a 9 and 10 intelligence" is a strawman, that's not what I'm talking about.
I'm done with this conversation. If you refuse to accept that a 5 intelligence is significantly different than a 20 then your view relative intelligence is so alien to me I don't even know where to start.
Ok, if you want to argue that somebody who is 5'9" is one inch taller than somebody who is 5'8" I'm right there with you.
But what is the difference,
according to the rules or even 'guidance', between somebody who has 8 Int and 10 Int?
Yes, the 10 Int person is better at recall, deduction, etc. But how much better and, more importantly, how is that supposed to be reflected in gameplay and roleplaying, again according to the rules which you insist dictate something about this?
I've argued the 8 Int is 5% worse than the 10 Int, because that's what the mechanic says. If you have a different number I'd love to hear your reasoning, but for now I'll go with the 5%.
The issue seems to be that the player with the low Int still tries to use their own intelligence when proposing plans, solving puzzles, piecing together clues, etc. So how do we roleplay being 5% dumber?
1. Suggest ideas that are 5% worse than the ideas from the person with 10 Int? Honestly I have absolutely zero notion of how this could work, of how you could make your ideas 5% worse. But I'm open to learning something.
2. Suggest good ideas 5% less often. That is, 1 in 20 times that you have a good idea, keep your mouth shut. Or, better yet, offer a bad idea. Of course, offering a bad idea should be worth double credit, so if you're going to actively play "stupid" maybe you only have to do that 1 in 40 times.
Ok, I can't keep this up. This is all completely idiotic of course. There just isn't a credible argument to be made that there is an objectively correct way to roleplay any Intelligence score. And this is true whether we are talking about 8 vs. 10, or 5 vs 20. The only correct way to roleplay any score is whatever the player thinks it should be.
Now, you may have personal preferences about how those scores should be represented, and that's fine. And you may not want to game with people who have different preferences, and that's also fine.
But your notion that the rules demand Intelligence (or Charisma or Dexterity or Strength or anything else) be roleplayed a
particular way, or even
within a particular range, is pure fantasy.