They did it because it's more profitable to shovel slop than to distribute quality. Quality content is expensive to make. Slop isn't. The way you do that is by hypnotizing people with addiction. To do that you have to have control over what people see and use algorithms to optimize that to "maximize engagement." You need your users mindlessly scrolling, not searching and categorizing and exploring. You need to disengage the neocortex and engage the brain stem.
TikTok is being copied by everyone because they nailed this formula better than anyone. They didn't invent it, just perfected it. I'd say Meta/Facebook invented it, which is why Zuckerberg should be known as the man who destroyed the Internet.
The next step beyond TikTok is a 100% AI generated algorithmic feed. Drop the human creators entirely. Everyone gets a personalized feed of low-quality AI slop tuned for maximum engagement.
Addiction is the best business model.