Several tried. Nothing as elaborate as cross dissemination, federation or whatever. But at least 5 to 10 years ago it proved to be almost impossible. Platforms like Rooster teeth, which was 100% subscription based, I think never broke even and still relied on YT ads for the majority of the revenue. Some big and small channels tried to at least just catalog, archive and serve their own videos and the costs still became astronomical really fast. Whenever you see one of those very old channels, most of them don’t conserve copies, let alone original source footage of their entire material. Everyone just delete their videos once they’ve been on YouTube for a month or so now, and they have to download their own videos when they want to reuse old footage.
Storage is cheap today, yes, but video really eats storage at an alarming rate. Specially now that 4k is the standard. So you have to reuse storage over and over. Transcoding is also really fast and optimized with modern algorithms, but it takes specialized graphical cards and data centers charge a premium to use servers with such capacities. Self hosting will never be able to satisfy a moderate demand. Get anything above 100 users simultaneously transcoding videos and a non-specialized server will halt to a grind just on IO calls to hard drives alone.
Once you consider all those factors it is obvious why YouTube is such a miracle.
Unless we invent cold fusion between the next 5 years, they will never be economical. They are the most energy inefficient thing ever invented by humanity and all prediction models state that it will cost more energy, not less, to keep making them better. They will never be energy efficient nor economical in their current state, and most companies are out of ideas on how to shake it up. Even the people who created generative models agree that they have just been brute forcing by making the models larger with more energy consumption. When you try to make them smaller or more energy efficient, they fall off the performance cliff and only produce garbage. I’m sure there are researchers doing cool stuff, but it is neither economical nor efficient.