The reality is that leveraging closed networks to gain effective monopolies (with all their known harmful effects) is a winning strategy with little counter strategies.

Users cannot switch to another OS because if they do they won't be able to communicate with social circle. This is also completely artificial because the networks have otherwise pretty much the same feature sets and are only distinguished by their accreted userbase.

Concurrent cannot compete because they can't gain enough users to get a critical mass

I wager that no single entity should have so many captive users.

Regulation is clearly in order