The iPhone is not primarily a telephone. If you are going to argue that it is, you really aren’t being reasonable.
Also, if you look at the history, you’ll discover that these innovations were all held back by regulation and the fixed nature of the phone system.
Nonsensical distinction. The common person sends and receives SMS using their telephone, using the same phone numbers used to call people, with the same disregard for whether they and the recipient use the same phone company because, like telephone calls, SMS works across companies. When you port your phone number to a new phone company, you continue to receive SMS sent to your number just as you do phone calls.
(And in actual fact, there are phone companies that do offer SMS service to landline phones.)
That your definition of ‘phone’ is meaningless. If phones can have any capability you like, then ‘phone’ doesn’t mean anything.
Once you are playing that game you may as well just declare that social networks can be regulated because they are a ‘capability some things that can also communicate with phones have’, and phones are already regulated.
So not actually part of what it means to be a phone then.