This works until you have children. My sister's daughter would cry as a young baby if she was around loud people for too long of a time, and would be happy when I put her in the other room in her car seat. She needed that down time.
My SP started walking furniture at 6 months and walking at 8 (most kids are around 11 - 13 months) No one would ever confuse her with an SJ.
My IJ has been obviously IJ her whole life. When she was 10 months old she was so frustrated she couldn't walk but wouldn't start until she could walk perfectly. She told me as a 10 year old that she wished there wasn't phone or email because she talked too much at school already.
My little EP has always loved people and been energized by being with and around people.