But you are also missing item 3, monetization. Alphabet turns practically free into something they can make money off of with advertising. People who are popular enough on YouTube get paid for what they make. It may not be a lot, but it is more than having to pay to get your video hosted.
And those content creators that strike out on their own platforms typically put their content behind a paywall to fund the cost to develop and distribute their work.
The cost for the system may be practically free, but it isn’t actually free.