1. They are supported by paying customers (the advertisers), not just VC money.

2. You don’t need to get rid of VCs, it’s orthogonal.

Just make interoperation/complete API coverage required by law to be available to any user if you have more users than certain amount. It would neuter the lock-in when anyone can make a third-party GUI that has no ads and interoperates with any other social platform (meaning no “all my friends are there” effect).