The problems with social media aren't its capacity or limitations - it absolutely can be at least as good as books for long-term, coherent narrative building and multistep reasoning. The problems are the incentives against using social media for fostering and sharing deep experiences and thought. Hundreds of billions of dollars are spent yearly promoting disposable, reactionary content, at the expense of robust, complex work that's risky to create and takes time to engage with. The moneymen want the money now, their future selves and their own children be damned.