It applies to every form...Harlan has written comics, too, y'know.
One of the lesser known phenomenon (if it could be called that) associated with the Marvel Expansion of the late 80s and early 90s was that editors hired writers with no credentials to speak of as long as they were willing to share some of the page rate with them.
Otherwise known as kickbacks.
So, that's one way Harlan's rant applies to comics.
In my own experience...
A few years back, a UK publishing company that holds the Stargate license contacted me about writing an SG-1 novel (they weren't allowed to distribute them in the states at the time).
The editor wanted me to write a lengthy plot outline and thirty sample pages.
Something along the lines of 40 or 50 pages on spec.
When I inquired as to the pay rate, she quoted a pretty low-end sum.
I pointed that out to her, and her response was essentially there were plenty of fan writers who were willing to work for less. Nay, desperate to work for less.
I suggested she go to one of them then and leave the professionals alone.
Harlan Ellison did comics? NO WAY! [/sarcasm]
The question was in relevance to writers just starting out offering artists half the profit in order to lure them to do the art for their comic. I get the "must pay" issue, but would that arrangement be okay?
That's pretty insightful... Because if you choose to do something you enjoy for a living then you should expect it to put food on the table.