It's going to happen. These platforms are so large they encompass a signification amount of the communication market .. and I don't say that lightly. Look at how Facebook has literally gobbled up all its competition and now is pushing policies that make WhatsApp and Oculus useless without handing over full control of all your accounts and devices?
These companies ARE STATES! They may not look like governments, but the communication power they wield is stronger than many nations.
You can no longer just say "They're private companies" when you literally cannot buy a well supported Mobile device unless it runs Android or iOS, unless you have the skill, ability and time to run something like a PinePhone or PostmarketOS.