> "Before breaking them up, we should see whether they are not just disrupted by a small player beating them out of the market" How long do you wait to see if this happens? E.g. MySpace was the social network back in the day. When was the last time you even heard/thought about MySpace let alone even visited the site? Did we wait long enough for MySpce to die on its own, or should we have acted sooner? Does it matter…
Your solutions are not enough because Facebook owns Instagram and WhatsApp - they buy out new social media so they're always in control. In Europe at least everyone uses WhatsApp and no-one texts anymore - they're too pervasive to avoid.
WhatsApp was a startup competitor at one stage too - it competed well enough to grow big enough to compete with Facebook & Google. Sure Facebook brought them out, but what is to stop the next WhatsApp? Likewise MySpace was too pervasive not to use at one point too, yet look at what happened to that when this little cool new thing called Facebook appeared.
Basically it comes down to user behavior, not any explicit "control" that Facebook et al have over individual's use of the internet.