Today it's easier than ever to create e.g. a decentralized or independent means of doing pretty much anything that could easily let people escape those walled gardens, if they wanted. The problem is people don't want to: FOMO. If they leave the walled garden, they have the Fear Of Missing Out on what's happening inside the walled garden.
You can even see this phenomena in real life. You have a dozen people at a table or whatever. Unless you have some good sample bias, a good chunk of them will be constantly glancing at their phones if not having their noses glued to them. You have significant things that could be happening in your immediate vicinity, supplanted out of concern for missing what are invariably trivialities in a mostly fake world.
This is a people problem - not a business or technology problem. And the worst part is that it's so incredibly insidious that people don't realize the harm involved. A person addicted to gambling will trend towards the same thing as a person addicted to drugs - losing everything they have. And so it's quite easy to see the consequences. A person who's mind is increasingly fogged and attention driven entirely to the pale glow of that screen and the little dopamine bumps it provides, by contrast, will see no immediately visible negative effects. And the addiction is so ubiquitous that even as consequences do begin to emerge, they're not really noted because it's 'normal.'