I know a very intelligent and intellectual ISFP. He's one of the most intellectual people I know, and he specialises in the sciences oddly enough.
Mind you, he recently graduated from a masters and everyone thought he'd do a doctorate, but apparently he's looking for a job. He used to have to study really hard for his parents and I wonder if he didn't actually want to be doing any of that before but just studied hard for a quiet life. He's very private and enigmatic, so we may never know.
My mum is also ISFP. I wouldn't say she was intellectual. I don't think she's ever felt the need to be academically successful; as an academic person myself I know she finds a lot of studying boring and pointless. I think 'dreamer' accurately sums her up, and studying is a big tiresome anchor, unless it's something she enjoys (like arts, crafts, gardening and languages). Interestingly enough, like the ISFP friend mentioned above, she did science A-levels and started a science degree just to make her dad happy - even though she hated sciences. She dropped out of uni, but only to marry her first husband, which didn't last long.