One example of an early honorary degree (the one the authors of said article probably found with a quick search in Wikipedia) doesn't capture the practice through the centuries, nor how it was established and used in other countries.
There's a difference between "first" and "representative of how a thing caught-on and came to be established and practiced" -- the first uses might not be representative of neither the reason for widespread adoption nor current use.
There are countries whose universities need (and do) no marketing at all otherwise, because they are public and state sponsored, but still give honorary degrees to honour important contributors from outside the academic field.
And the very same article addresses that point as well. From the first one granted in the 15th century to the most recent granted a few months ago, honorary degrees are extremely highly correlated with the important contribution the individual made to the university's coffers, or secondarily to people whose names lend some sort of beneficial aspect to the university. I just looked up my doctoral university's list of awardees, and by coincidence, wouldn't you know that one of their names is on the college of business and another on the relatively newly formed institute of technology. What are the odds? :)
