I have been playing with guest account options, and it is my belief that this can be done with OAuth, a database and a handfull of 'guest accounts' per project.
Posting the comment can be done by a 'company account' and the post can include author name (name and profile pic from social media login).
I have managed this on a wordpress blog with the Auth0 plugin and a Chron Posting Script. This leads us to a future of guest/lite/full accounts.
Here I have done a post response about how I believe guest accounts can be implemented technically for the most effect.