Also ... i dont like that stat being called Intelligence to be honest, it seem like everyone i know expect characters with lower intelligence to be at least demented or something. -_- Yet intelligence is much more than ability to make whole, complement senteces ... its about your character memory (therefore remembering more spells for a day), abylity to learn new things, abylity to understand so far unknown things, or solve problems, etc. :-/ Not every barbarian who have intelligence 8 have to be Neanderthal telling just "me smash, me eat". :-/
Im sorry, its certainly interesting topic to talk about, but it seem to me impossible, and kinda childish to try determine exact spot where role play ends, and power play starts.
Of all the ability scores I always thought INT was the most accurate because it’s exactly those things you described. Low intelligence doesn’t mean your character is demented or crazy. They are slow. Forrest Gump would have an INT of roughly 8 (I think his IQ was 83 in the movie). He was just somewhat slower grasping ideas but he wasn’t crazy or completely useless.
And again. Roleplay and power gaming are not mutually exclusive. One does not have to stop for the other to start. They can both happen together.
