Why does GitHub recommend HTTPS over SSH?

Question

On the GitHub site there is a link...

https://help.github.com/articles/generating-ssh-keys

... and it states...

If you have decided no

Answer 1

Also see: the official Which remote URL should I use? answer on help.github.com.

EDIT:

It seems that it's no longer necessary to have write access to a public repo to use an SSH URL, rendering my original explanation invalid.

ORIGINAL:

Apparently the main reason for favoring HTTPS URLs is that SSH URL's won't work with a public repo if you don't have write access to that repo.

The use of SSH URLs is encouraged for deployment to production servers, however - presumably the context here is services like Heroku.