Breaking them up won't solve anything. Youtube and Facebook are huge specifically because of their network effects. In the case of Youtube without something like ActivityPub aggregating all the different video services into one inevitably some other company will gather more users, thus becoming the more profitable platform for creators, thus attracting more creators which will attract more users.
There's also the question of can something like youtube, where there's pretty much no restrictions on who can upload and how much they can upload, be profitable at a smaller scale or without being the subsidiary of a larger corporation with another huge money pipe?
There's also the question of can something like youtube, where there's pretty much no restrictions on who can upload and how much they can upload, be profitable at a smaller scale or without being the subsidiary of a larger corporation with another huge money pipe?