I don't really get the first point about scale and brand, because the examples you give like email are built on open protocols, so it's the protocol itself that is the brand. I don't need a particular brand of email client to send emails to someone.
Yes, but the choice has to be made to use email rather than Facebook, iMessage, LinkedIn, etc. For some people it's the default, but there is always advertising trying to tempt them away. Email doesn't really have a brand identity.
Note how easily email converges on big email providers too, rather than everyone running their own services. Gmail is definitely a brand. Lo and behold, Gmail is a service that is "free" but paid for by selling analysis of the content of your emails.
