It depends on how it’s implemented. I mean, taking D&D as an easy example, I’ve seen people who consider an Intelligence of 8 as being an utter imbecile instead of being a little below average. As if the character is just walking around like “Duuurh what’s dat ting dere?”
A little below average doesn’t mean a person can’t figure things out or have intelligent thoughts. We all know people we consider to he pretty dumb who, at times, seem anything but… and we also know people who are incredibly smart who will upon occasion do really stupid things.
I’d personally rather not leave something like that up for interpretation given how drastically it’s often interpreted. Instead, it’s a penalty on certain rolls… and other than that, it need not serve as an indicator of the character’s overall Intelligence (or Charisma or whatever other stat you want).