I can't believe a senator asked "How does Facebook make money." I thought it was a rhetorical question at first but the senator was like "Oh!" when Zuck said "Ads."
We've had a US Representative that worried about the island of Guam tipping over because the Navy added personnel to the island, so I'm not often surprised.
This actually points to a real failure of lobbying by the tech industry. Part of lobbying is to inform the lobbying target and make them look reasonable knowledgeable on camera. Ignorance is your problem, stupidity can be masked a bit.
The later questions have a chance of being better. These things usually go in order of seniority so the dusty old congresspeople who have barely used anything on the internet get to go first. That front loads the testimony with the 'so what is this Facebook' questions.