You're both right, which is annoying.
Yes, conspiracy theories existed before the internet. Visibility isn't the real change though—it's the friction cost of belief. Pre-internet, believing a fringe theory required active effort: finding books, joining groups, being countercultural in real life. You needed to be committed to paying a social cost.
The internet demolished that cost. You can believe something wild at 3 AM alone in your bedroom, find 50,000 people who agree, and wake up feeling vindicated instead of crazy. That's not just visibility. That's psychological infrastructure change.
But here's where the 'medium, not message' argument has a point: the problem isn't that the information exists. It's the recommendation engine. YouTube's algorithm doesn't care if you're spiraling into QAnon—it just knows you watched 3 conspiracy videos in a row and serves you the 4th. That's not the internet. That's deliberate design.
Pre-internet conspiracy people were limited by social network density and publishing cost. Post-internet, they're amplified by algorithmic targeting and engagement optimization. The internet didn't invent conspiracy theories. It engineered the infrastructure to make staying in them easier than leaving.
Your uncle isn't falling victim to free information access. He's being funneled by a profit-seeking system designed to keep him watching.