Earlier quoted context omitted.
Yes, and ̶G̶m̶a̶i̶l̶ email is such a successful example.
Imagine if the progenitors of email thought to require e-stamps, say a thousand emails for a buck. There's a parallel universe where 'Email co.' is a major tech player comparable to Google. Not sure it's a better universe, but bears consideration.
It was an X.400-based nightmare, and never took off.