Opening up the social graph seems almost exclusively a privacy concern. The examples you bring up between Instagram / Twitter are primarily about marketing and

Opening up the social graph seems almost exclusively a privacy concern. The examples you bring up between Instagram / Twitter are primarily about marketing and onboarding new users to competing services. This isn't actually going to lead to much user conversion unless the competing service is actually meaningfully more interesting. If it is meaningfully more interesting, then users will share it on their own (see Tik Tok), rather demonstrating that regulating the social graph is completely pointless.